If the a element has an href attribute, then it represents a hyperlink (a hypertext anchor) labeled by its contents. If the a element has no href attribute, then the element represents a placeholder for where a link might otherwise have been placed, if it had been relevant, consisting of just the element's contents. The target, download, ping, rel, hreflang, type, and referrerpolicy attributes must be omitted if the href attribute is not present. If the itemprop attribute is specified on an a element, then the href attribute must also be specified. The href, target, download, ping, and referrerpolicy attributes affect what happens when users follow hyperlinks or download hyperlinks created using the a element. The rel, hreflang, and type attributes may be used to indicate to the user the likely nature of the target resource before the user follows the link. The activation behavior of an a element element given an event event is: If element has no href attribute, then return.Let hyperlinkSuffix be null.If event's target is an img with an ismap attribute specified, then: Let x and y be 0.If event's isTrusted attribute is initialized to true, then set x to the distance in CSS pixels from the left edge of the image to the location of the click, and set y to the distance in CSS pixels from the top edge of the image to the location of the click.If x is negative, set x to 0.If y is negative, set y to 0.Set hyperlinkSuffix to the concatenation of U+003F (?), the value of x expressed as a base-ten integer using ASCII digits, U+002C (,), and the value of y expressed as a base-ten integer using ASCII digits. If element has a download attribute, or if the user has expressed a preference to download the hyperlink, then download the hyperlink created by element given hyperlinkSuffix.Otherwise, follow the hyperlink created by element given hyperlinkSuffix. The IDL attributes download, ping, target, rel, hreflang, and type, must reflect the respective content attributes of the same name. The IDL attribute relList must reflect the rel content attribute. The IDL attribute referrerPolicy must reflect the referrerpolicy content attribute, limited to only known values. The text attribute's getter must return this element's descendant text content. The text attribute's setter must string replace all with the given value within this element.

The abbr element represents an abbreviation or acronym, optionally with its expansion. The title attribute may be used to provide an expansion of the abbreviation. The attribute, if specified, must contain an expansion of the abbreviation, and nothing else. If an abbreviation is pluralized, the expansion's grammatical number (plural vs singular) must match the grammatical number of the contents of the element. Abbreviations do not have to be marked up using this element. It is expected to be useful in the following cases: Abbreviations for which the author wants to give expansions, where using the abbr element with a title attribute is an alternative to including the expansion inline (e.g. in parentheses).Abbreviations that are likely to be unfamiliar to the document's readers, for which authors are encouraged to either mark up the abbreviation using an abbr element with a title attribute or include the expansion inline in the text the first time the abbreviation is used.Abbreviations whose presence needs to be semantically annotated, e.g. so that they can be identified from a style sheet and given specific styles, for which the abbr element can be used without a title attribute. Providing an expansion in a title attribute once will not necessarily cause other abbr elements in the same document with the same contents but without a title attribute to behave as if they had the same expansion. Every abbr element is independent.

The address element represents the contact information for its nearest article or body element ancestor. If that is the body element, then the contact information applies to the document as a whole. The address element must not be used to represent arbitrary addresses (e.g. postal addresses), unless those addresses are in fact the relevant contact information. (The p element is the appropriate element for marking up postal addresses in general.) The address element must not contain information other than contact information. Typically, the address element would be included along with other information in a footer element. The contact information for a node node is a collection of address elements defined by the first applicable entry from the following list: If node is an article elementIf node is a body element The contact information consists of all the address elements that have node as an ancestor and do not have another body or article element ancestor that is a descendant of node. If node has an ancestor element that is an article elementIf node has an ancestor element that is a body element The contact information of node is the same as the contact information of the nearest article or body element ancestor, whichever is nearest. If node's node document has a body element The contact information of node is the same as the contact information of the body element of the Document. Otherwise There is no contact information for node. User agents may expose the contact information of a node to the user, or use it for other purposes, such as indexing sections based on the sections' contact information.

The area element represents either a hyperlink with some text and a corresponding area on an image map, or a dead area on an image map. An area element with a parent node must have a map element ancestor. If the area element has an href attribute, then the area element represents a hyperlink. In this case, the alt attribute must be present. It specifies the text of the hyperlink. Its value must be text that, when presented with the texts specified for the other hyperlinks of the image map, and with the alternative text of the image, but without the image itself, provides the user with the same kind of choice as the hyperlink would when used without its text but with its shape applied to the image. The alt attribute may be left blank if there is another area element in the same image map that points to the same resource and has a non-blank alt attribute. If the area element has no href attribute, then the area represented by the element cannot be selected, and the alt attribute must be omitted. In both cases, the shape and coords attributes specify the area. The shape attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The states given in the first cell of the rows with keywords give the states to which those keywords map. Some of the keywords are non-conforming, as noted in the last column. State Keywords Notes Circle state circle circ Non-conforming Default state default Polygon state poly polygon Non-conforming Rectangle state rect rectangle Non-conforming The attribute may be omitted. The missing value default and invalid value default are the rectangle state. The coords attribute must, if specified, contain a valid list of floating-point numbers. This attribute gives the coordinates for the shape described by the shape attribute. The processing for this attribute is described as part of the image map processing model. In the circle state, area elements must have a coords attribute present, with three integers, the last of which must be non-negative. The first integer must be the distance in CSS pixels from the left edge of the image to the center of the circle, the second integer must be the distance in CSS pixels from the top edge of the image to the center of the circle, and the third integer must be the radius of the circle, again in CSS pixels. In the default state state, area elements must not have a coords attribute. (The area is the whole image.) In the polygon state, area elements must have a coords attribute with at least six integers, and the number of integers must be even. Each pair of integers must represent a coordinate given as the distances from the left and the top of the image in CSS pixels respectively, and all the coordinates together must represent the points of the polygon, in order. In the rectangle state, area elements must have a coords attribute with exactly four integers, the first of which must be less than the third, and the second of which must be less than the fourth. The four points must represent, respectively, the distance from the left edge of the image to the left side of the rectangle, the distance from the top edge to the top side, the distance from the left edge to the right side, and the distance from the top edge to the bottom side, all in CSS pixels. When user agents allow users to follow hyperlinks or download hyperlinks created using the area element, as described in the next section, the href, target, download, and ping attributes decide how the link is followed. The rel attribute may be used to indicate to the user the likely nature of the target resource before the user follows the link. The target, download, ping, rel, and referrerpolicy attributes must be omitted if the href attribute is not present. If the itemprop attribute is specified on an area element, then the href attribute must also be specified. The activation behavior of an area element element is: If element has no href attribute, then return.If element has a download attribute, or if the user has expressed a preference to download the hyperlink, then download the hyperlink created by element.Otherwise, follow the hyperlink created by element. The IDL attributes alt, coords, target, download, ping, and rel, each must reflect the respective content attributes of the same name. The IDL attribute shape must reflect the shape content attribute. The IDL attribute relList must reflect the rel content attribute. The IDL attribute referrerPolicy must reflect the referrerpolicy content attribute, limited to only known values.

The article element represents a complete, or self-contained, composition in a document, page, application, or site and that is, in principle, independently distributable or reusable, e.g. in syndication. This could be a forum post, a magazine or newspaper article, a blog entry, a user-submitted comment, an interactive widget or gadget, or any other independent item of content. When article elements are nested, the inner article elements represent articles that are in principle related to the contents of the outer article. For instance, a blog entry on a site that accepts user-submitted comments could represent the comments as article elements nested within the article element for the blog entry. Author information associated with an article element (q.v. the address element) does not apply to nested article elements. When the main content of the page (i.e. excluding footers, headers, navigation blocks, and sidebars) is all one single self-contained composition, that content may be marked with an article, but it is technically redundant in that case (since it's self-evident that the page is a single composition, as it is a single document).

The aside element represents a section of a page that consists of content that is tangentially related to the content around the aside element, and which could be considered separate from that content. Such sections are often represented as sidebars in printed typography. The element can be used for typographical effects like pull quotes or sidebars, for advertising, for groups of nav elements, and for other content that is considered separate from the main content of the page.

An audio element represents a sound or audio stream. Content may be provided inside the audio element. User agents should not show this content to the user; it is intended for older web browsers which do not support audio, so that legacy audio plugins can be tried, or to show text to the users of these older browsers informing them of how to access the audio contents. The audio element is a media element whose media data is ostensibly audio data. The src, crossorigin, preload, autoplay, loop, muted, and controls attributes are the attributes common to all media elements. A legacy factory function is provided for creating HTMLAudioElement objects (in addition to the factory methods from DOM such as createElement()): Audio(src). When invoked, the legacy factory function must perform the following steps: Let document be the current global object's associated Document.Let audio be the result of creating an element given document, audio, and the HTML namespace.Set an attribute value for audio using "preload" and "auto".If src is given, then set an attribute value for audio using "src" and src. (This will cause the user agent to invoke the object's resource selection algorithm before returning.)Return audio.

The b element represents a span of text to which attention is being drawn for utilitarian purposes without conveying any extra importance and with no implication of an alternate voice or mood, such as key words in a document abstract, product names in a review, actionable words in interactive text-driven software, or an article lede. As with the i element, authors can use the class attribute on the b element to identify why the element is being used, so that if the style of a particular use is to be changed at a later date, the author doesn't have to go through annotating each use. The b element should be used as a last resort when no other element is more appropriate. In particular, headings should use the h1 to h6 elements, stress emphasis should use the em element, importance should be denoted with the strong element, and text marked or highlighted should use the mark element.

The base element allows authors to specify the document base URL for the purposes of parsing URLs, and the name of the default browsing context for the purposes of following hyperlinks. The element does not represent any content beyond this information. There must be no more than one base element per document. A base element must have either an href attribute, a target attribute, or both. The href content attribute, if specified, must contain a valid URL potentially surrounded by spaces. A base element, if it has an href attribute, must come before any other elements in the tree that have attributes defined as taking URLs, except the html element (its manifest attribute isn't affected by base elements). The target attribute, if specified, must contain a valid browsing context name or keyword, which specifies which browsing context is to be used as the default when hyperlinks and forms in the Document cause navigation. A base element, if it has a target attribute, must come before any elements in the tree that represent hyperlinks. To get an element's target, given an a, area, or form element element, run these steps: If element has a target attribute, then return that attribute's value.If element's node document contains a base element with a target attribute, then return the value of the target attribute of the first such base element.Return the empty string. A base element that is the first base element with an href content attribute in a document tree has a frozen base URL. The frozen base URL must be immediately set for an element whenever any of the following situations occur: The base element becomes the first base element in tree order with an href content attribute in its Document.The base element is the first base element in tree order with an href content attribute in its Document, and its href content attribute is changed. To set the frozen base URL for an element element: Let document be element's node document. Let urlRecord be the result of parsing the value of element's href content attribute with document's fallback base URL, and document's character encoding. (Thus, the base element isn't affected by itself.)Set element's frozen base URL to document's fallback base URL, if urlRecord is failure or running Is base allowed for Document? on the resulting URL record and document returns "Blocked", and to urlRecord otherwise. The href IDL attribute, on getting, must return the result of running the following algorithm: Let document be element's node document. Let url be the value of the href attribute of this element, if it has one, and the empty string otherwise.Let urlRecord be the result of parsing url with document's fallback base URL, and document's character encoding. (Thus, the base element isn't affected by other base elements or itself.)If urlRecord is failure, return url.Return the serialization of urlRecord. The href IDL attribute, on setting, must set the href content attribute to the given new value. The target IDL attribute must reflect the content attribute of the same name.

The bdi element represents a span of text that is to be isolated from its surroundings for the purposes of bidirectional text formatting. [BIDI]

The bdo element represents explicit text directionality formatting control for its children. It allows authors to override the Unicode bidirectional algorithm by explicitly specifying a direction override. [BIDI] Authors must specify the dir attribute on this element, with the value ltr to specify a left-to-right override and with the value rtl to specify a right-to-left override. The auto value must not be specified.

The blockquote element represents a section that is quoted from another source. Content inside a blockquote must be quoted from another source, whose address, if it has one, may be cited in the cite attribute. If the cite attribute is present, it must be a valid URL potentially surrounded by spaces. To obtain the corresponding citation link, the value of the attribute must be parsed relative to the element's node document. User agents may allow users to follow such citation links, but they are primarily intended for private use (e.g., by server-side scripts collecting statistics about a site's use of quotations), not for readers. The content of a blockquote may be abbreviated or may have context added in the conventional manner for the text's language. Attribution for the quotation, if any, must be placed outside the blockquote element. The cite IDL attribute must reflect the element's cite content attribute.

The body element represents the contents of the document. In conforming documents, there is only one body element. The document.body IDL attribute provides scripts with easy access to a document's body element. The body element exposes as event handler content attributes a number of the event handlers of the Window object. It also mirrors their event handler IDL attributes. The event handlers of the Window object named by the Window-reflecting body element event handler set, exposed on the body element, replace the generic event handlers with the same names normally supported by HTML elements. Thus, for example, a bubbling error event dispatched on a child of the body element of a Document would first trigger the onerror event handler content attributes of that element, then that of the root html element, and only then would it trigger the onerror event handler content attribute on the body element. This is because the event would bubble from the target, to the body, to the html, to the Document, to the Window, and the event handler on the body is watching the Window not the body. A regular event listener attached to the body using addEventListener(), however, would be run when the event bubbled through the body and not when it reaches the Window object.

The br element represents a line break. br elements must be used only for line breaks that are actually part of the content, as in poems or addresses. br elements must not be used for separating thematic groups in a paragraph. If a paragraph consists of nothing but a single br element, it represents a placeholder blank line (e.g. as in a template). Such blank lines must not be used for presentation purposes. Any content inside br elements must not be considered part of the surrounding text.

The button element represents a button labeled by its contents. The element is a button. The type attribute controls the behavior of the button when it is activated. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword. Keyword State Brief description submit Submit Button Submits the form. reset Reset Button Resets the form. button Button Does nothing. The missing value default and invalid value default are the Submit Button state. If the type attribute is in the Submit Button state, the element is specifically a submit button. Constraint validation: If the type attribute is in the Reset Button state or the Button state, the element is barred from constraint validation. A button element element's activation behavior is: If element is disabled, then return.If element does not have a form owner, then return.If element's node document is not fully active, then return. Switch on element's type attribute's state: Submit Button Submit element's form owner from element. Reset Button Reset element's form owner. Button Do nothing. The form attribute is used to explicitly associate the button element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The formaction, formenctype, formmethod, formnovalidate, and formtarget attributes are attributes for form submission. The formaction, formenctype, formmethod, formnovalidate, and formtarget must not be specified if the element's type attribute is not in the Submit Button state. The value attribute gives the element's value for the purposes of form submission. The element's value is the value of the element's value attribute, if there is one, or the empty string otherwise. The value IDL attribute must reflect the content attribute of the same name. The type IDL attribute must reflect the content attribute of the same name, limited to only known values. The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The disabled, form, and name IDL attributes are part of the element's forms API.

The canvas element provides scripts with a resolution-dependent bitmap canvas, which can be used for rendering graphs, game graphics, art, or other visual images on the fly. Authors should not use the canvas element in a document when a more suitable element is available. For example, it is inappropriate to use a canvas element to render a page heading: if the desired presentation of the heading is graphically intense, it should be marked up using appropriate elements (typically h1) and then styled using CSS and supporting technologies such as shadow trees. When authors use the canvas element, they must also provide content that, when presented to the user, conveys essentially the same function or purpose as the canvas's bitmap. This content may be placed as content of the canvas element. The contents of the canvas element, if any, are the element's fallback content. In interactive visual media, if scripting is enabled for the canvas element, and if support for canvas elements has been enabled, then the canvas element represents embedded content consisting of a dynamically created image, the element's bitmap. In non-interactive, static, visual media, if the canvas element has been previously associated with a rendering context (e.g. if the page was viewed in an interactive visual medium and is now being printed, or if some script that ran during the page layout process painted on the element), then the canvas element represents embedded content with the element's current bitmap and size. Otherwise, the element represents its fallback content instead. In non-visual media, and in visual media if scripting is disabled for the canvas element or if support for canvas elements has been disabled, the canvas element represents its fallback content instead. When a canvas element represents embedded content, the user can still focus descendants of the canvas element (in the fallback content). When an element is focused, it is the target of keyboard interaction events (even though the element itself is not visible). This allows authors to make an interactive canvas keyboard-accessible: authors should have a one-to-one mapping of interactive regions to focusable areas in the fallback content. (Focus has no effect on mouse interaction events.) [UIEVENTS] An element whose nearest canvas element ancestor is being rendered and represents embedded content is an element that is being used as relevant canvas fallback content. The canvas element has two attributes to control the size of the element's bitmap: width and height. These attributes, when specified, must have values that are valid non-negative integers. The rules for parsing non-negative integers must be used to obtain their numeric values. If an attribute is missing, or if parsing its value returns an error, then the default value must be used instead. The width attribute defaults to 300, and the height attribute defaults to 150. When setting the value of the width or height attribute, if the context mode of the canvas element is set to placeholder, the user agent must throw an "InvalidStateError" DOMException and leave the attribute's value unchanged. The intrinsic dimensions of the canvas element when it represents embedded content are equal to the dimensions of the element's bitmap. The user agent must use a square pixel density consisting of one pixel of image data per coordinate space unit for the bitmaps of a canvas and its rendering contexts. The bitmaps of canvas elements, the bitmaps of ImageBitmap objects, as well as some of the bitmaps of rendering contexts, such as those described in the sections on the CanvasRenderingContext2D and ImageBitmapRenderingContext objects below, have an origin-clean flag, which can be set to true or false. Initially, when the canvas element or ImageBitmap object is created, its bitmap's origin-clean flag must be set to true. A canvas element can have a rendering context bound to it. Initially, it does not have a bound rendering context. To keep track of whether it has a rendering context or not, and what kind of rendering context it is, a canvas also has a canvas context mode, which is initially none but can be changed to either placeholder, 2d, bitmaprenderer, webgl, webgl2, or webgpu by algorithms defined in this specification. When its canvas context mode is none, a canvas element has no rendering context, and its bitmap must be transparent black with an intrinsic width equal to the numeric value of the element's width attribute and an intrinsic height equal to the numeric value of the element's height attribute, those values being interpreted in CSS pixels, and being updated as the attributes are set, changed, or removed. When its canvas context mode is placeholder, a canvas element has no rendering context. It serves as a placeholder for an OffscreenCanvas object, and the content of the canvas element is updated by calling the commit() method of the OffscreenCanvas object's rendering context. When a canvas element represents embedded content, it provides a paint source whose width is the element's intrinsic width, whose height is the element's intrinsic height, and whose appearance is the element's bitmap. Whenever the width and height content attributes are set, removed, changed, or redundantly set to the value they already have, then the user agent must perform the action from the row of the following table that corresponds to the canvas element's context mode. Context Mode Action 2d Follow the steps to set bitmap dimensions to the numeric values of the width and height content attributes. webgl or webgl2 Follow the behavior defined in the WebGL specifications. [WEBGL] webgpu Follow the behavior defined in WebGPU. [WEBGPU] bitmaprenderer If the context's bitmap mode is set to blank, run the steps to set an ImageBitmapRenderingContext's output bitmap, passing the canvas element's rendering context. placeholder Do nothing. none Do nothing. The width and height IDL attributes must reflect the respective content attributes of the same name, with the same defaults. The getContext(contextId, options) method of the canvas element, when invoked, must run these steps: If options is not an object, then set options to null.Set options to the result of converting options to a JavaScript value. Run the steps in the cell of the following table whose column header matches this canvas element's canvas context mode and whose row header matches contextId: none 2d bitmaprenderer webgl or webgl2 webgpu placeholder "2d" Follow the 2D context creation algorithm defined in the section below, passing it this canvas element and options, to obtain a CanvasRenderingContext2D object; if this does not throw an exception, then set this canvas element's context mode to 2d, and return the CanvasRenderingContext2D object. Return the same object as was returned the last time the method was invoked with this same first argument. Return null. Return null. Return null. Throw an "InvalidStateError" DOMException. "bitmaprenderer" Follow the ImageBitmapRenderingContext creation algorithm defined in the section below, passing it this canvas element and options, to obtain an ImageBitmapRenderingContext object; then set this canvas element's context mode to bitmaprenderer, and return the ImageBitmapRenderingContext object. Return null. Return the same object as was returned the last time the method was invoked with this same first argument. Return null. Return null. Throw an "InvalidStateError" DOMException. "webgl" or "webgl2", if the user agent supports the WebGL feature in its current configuration Follow the instructions given in the WebGL specifications' Context Creation sections to obtain a WebGLRenderingContext, WebGL2RenderingContext, or null; if the returned value is null, then return null; otherwise, set this canvas element's context mode to webgl or webgl2, and return the WebGLRenderingContext or WebGL2RenderingContext object. [WEBGL] Return null. Return null. Return the same object as was returned the last time the method was invoked with this same first argument. Return null. Throw an "InvalidStateError" DOMException. "webgpu", if the user agent supports the WebGPU feature in its current configuration Follow the instructions given in WebGPU's Canvas Rendering section to obtain a GPUCanvasContext or null; if the returned value is null, then return null; otherwise, set this canvas element's context mode to webgpu and return the GPUCanvasContext object. [WEBGPU] Return null. Return null. Return null. Return the same object as was returned the last time the method was invoked with this same first argument. Throw an "InvalidStateError" DOMException. An unsupported value* Return null. Return null. Return null. Return null. Return null. Throw an "InvalidStateError" DOMException. * For example, the "webgl" or "webgl2" value in the case of a user agent having exhausted the graphics hardware's abilities and having no software fallback implementation. The toDataURL(type, quality) method, when invoked, must run these steps: If this canvas element's bitmap's origin-clean flag is set to false, then throw a "SecurityError" DOMException. If this canvas element's bitmap has no pixels (i.e. either its horizontal dimension or its vertical dimension is zero) then return the string "data:,". (This is the shortest data: URL; it represents the empty string in a text/plain resource.)Let file be a serialization of this canvas element's bitmap as a file, passing type and quality if given.If file is null then return "data:,".Return a data: URL representing file. [RFC2397] The toBlob(callback, type, quality) method, when invoked, must run these steps: If this canvas element's bitmap's origin-clean flag is set to false, then throw a "SecurityError" DOMException.Let result be null.If this canvas element's bitmap has pixels (i.e., neither its horizontal dimension nor its vertical dimension is zero), then set result to a copy of this canvas element's bitmap. Run these steps in parallel: If result is non-null, then set result to a serialization of result as a file with type and quality if given. Queue an element task on the canvas blob serialization task source given the canvas element to run these steps: If result is non-null, then set result to a new Blob object, created in the relevant Realm of this canvas element, representing result. [FILEAPI]Invoke callback with « result ». The transferControlToOffscreen() method, when invoked, must run these steps: If this canvas element's context mode is not set to none, throw an "InvalidStateError" DOMException.Let offscreenCanvas be a new OffscreenCanvas object with its width and height equal to the values of the width and height content attributes of this canvas element.Set the placeholder canvas element of offscreenCanvas to a weak reference to this canvas element.Set this canvas element's context mode to placeholder.Return offscreenCanvas.

The caption element represents the title of the table that is its parent, if it has a parent and that is a table element. The caption element takes part in the table model. When a table element is the only content in a figure element other than the figcaption, the caption element should be omitted in favor of the figcaption. A caption can introduce context for a table, making it significantly easier to understand.

The cite element represents the title of a work (e.g. a book, a paper, an essay, a poem, a score, a song, a script, a film, a TV show, a game, a sculpture, a painting, a theatre production, a play, an opera, a musical, an exhibition, a legal case report, a computer program, etc.). This can be a work that is being quoted or referenced in detail (i.e., a citation), or it can just be a work that is mentioned in passing. A person's name is not the title of a work — even if people call that person a piece of work — and the element must therefore not be used to mark up people's names. (In some cases, the b element might be appropriate for names; e.g. in a gossip article where the names of famous people are keywords rendered with a different style to draw attention to them. In other cases, if an element is really needed, the span element can be used.)

The code element represents a fragment of computer code. This could be an XML element name, a filename, a computer program, or any other string that a computer would recognize. There is no formal way to indicate the language of computer code being marked up. Authors who wish to mark code elements with the language used, e.g. so that syntax highlighting scripts can use the right rules, can use the class attribute, e.g. by adding a class prefixed with "language-" to the element.

If a col element has a parent and that is a colgroup element that itself has a parent that is a table element, then the col element represents one or more columns in the column group represented by that colgroup. The element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero and less than or equal to 1000. The col element and its span attribute take part in the table model. The span IDL attribute must reflect the content attribute of the same name. It is clamped to the range [1, 1000], and its default value is 1.

The colgroup element represents a group of one or more columns in the table that is its parent, if it has a parent and that is a table element. If the colgroup element contains no col elements, then the element may have a span content attribute specified, whose value must be a valid non-negative integer greater than zero and less than or equal to 1000. The colgroup element and its span attribute take part in the table model. The span IDL attribute must reflect the content attribute of the same name. It is clamped to the range [1, 1000], and its default value is 1.

The data element represents its contents, along with a machine-readable form of those contents in the value attribute. The value attribute must be present. Its value must be a representation of the element's contents in a machine-readable format. The element can be used for several purposes. When combined with microformats or the microdata attributes defined in this specification, the element serves to provide both a machine-readable value for the purposes of data processors, and a human-readable value for the purposes of rendering in a web browser. In this case, the format to be used in the value attribute is determined by the microformats or microdata vocabulary in use. The element can also, however, be used in conjunction with scripts in the page, for when a script has a literal value to store alongside a human-readable value. In such cases, the format to be used depends only on the needs of the script. (The data-* attributes can also be useful in such situations.) The value IDL attribute must reflect the content attribute of the same name.

The datalist element represents a set of option elements that represent predefined options for other controls. In the rendering, the datalist element represents nothing and it, along with its children, should be hidden. The datalist element can be used in two ways. In the simplest case, the datalist element has just option element children. In the more elaborate case, the datalist element can be given contents that are to be displayed for down-level clients that don't support datalist. In this case, the option elements are provided inside a select element inside the datalist element. The datalist element is hooked up to an input element using the list attribute on the input element. Each option element that is a descendant of the datalist element, that is not disabled, and whose value is a string that isn't the empty string, represents a suggestion. Each suggestion has a value and a label. The options IDL attribute must return an HTMLCollection rooted at the datalist node, whose filter matches option elements. Constraint validation: If an element has a datalist element ancestor, it is barred from constraint validation.

The dd element represents the description, definition, or value, part of a term-description group in a description list (dl element).

The del element represents a removal from the document. del elements should not cross implied paragraph boundaries.

The details element represents a disclosure widget from which the user can obtain additional information or controls. The first summary element child of the element, if any, represents the summary or legend of the details. If there is no child summary element, the user agent should provide its own legend (e.g. "Details"). The rest of the element's contents represents the additional information or controls. The open content attribute is a boolean attribute. If present, it indicates that both the summary and the additional information is to be shown to the user. If the attribute is absent, only the summary is to be shown. When the element is created, if the attribute is absent, the additional information should be hidden; if the attribute is present, that information should be shown. Subsequently, if the attribute is removed, then the information should be hidden; if the attribute is added, the information should be shown. The user agent should allow the user to request that the additional information be shown or hidden. To honor a request for the details to be shown, the user agent must set the open attribute on the element to the empty string. To honor a request for the information to be hidden, the user agent must remove the open attribute from the element. Whenever the open attribute is added to or removed from a details element, the user agent must queue an element task on the DOM manipulation task source given then details element that runs the following steps, which are known as the details notification task steps, for this details element: If another task has been queued to run the details notification task steps for this details element, then return. Fire an event named toggle at the details element. The open IDL attribute must reflect the open content attribute. The ancestor details revealing algorithm is to run the following steps on currentNode: While currentNode has a parent node within the flat tree: If currentNode is slotted into the second slot of a details element: Set currentNode to the details element which currentNode is slotted into.If the open attribute is not set on currentNode, then set the open attribute on currentNode to the empty string. Otherwise, set currentNode to the parent node of currentNode within the flat tree.

The dfn element represents the defining instance of a term. The paragraph, description list group, or section that is the nearest ancestor of the dfn element must also contain the definition(s) for the term given by the dfn element. Defining term: if the dfn element has a title attribute, then the exact value of that attribute is the term being defined. Otherwise, if it contains exactly one element child node and no child Text nodes, and that child element is an abbr element with a title attribute, then the exact value of that attribute is the term being defined. Otherwise, it is the descendant text content of the dfn element that gives the term being defined. If the title attribute of the dfn element is present, then it must contain only the term being defined. An a element that links to a dfn element represents an instance of the term defined by the dfn element.

The dialog element represents a part of an application that a user interacts with to perform a task, for example a dialog box, inspector, or window. The open attribute is a boolean attribute. When specified, it indicates that the dialog element is active and that the user can interact with it. A dialog element without an open attribute specified should not be shown to the user. This requirement may be implemented indirectly through the style layer. For example, user agents that support the suggested default rendering implement this requirement using the CSS rules described in the Rendering section. Removing the open attribute will usually hide the dialog. However, doing so has a number of strange additional consequences: The close event will not be fired.The close() method, and any user-agent provided cancelation interface, will no longer be able to close the dialog.If the dialog was shown using its showModal() method, the Document will still be blocked. For these reasons, it is generally better to never remove the open attribute manually. Instead, use the close() method to close the dialog, or the hidden attribute to hide it. The tabindex attribute must not be specified on dialog elements. When the show() method is invoked, the user agent must run the following steps: If the element already has an open attribute, then return.Add an open attribute to the dialog element, whose value is the empty string.Set the dialog element's previously focused element to the focused element.Run the dialog focusing steps for the dialog element. When the showModal() method is invoked, the user agent must run the following steps: Let subject be the dialog element on which the method was invoked.If subject already has an open attribute, then throw an "InvalidStateError" DOMException.If subject is not connected, then throw an "InvalidStateError" DOMException.Add an open attribute to subject, whose value is the empty string.Set the is modal flag of subject to true. Let subject's node document be blocked by the modal dialog subject. If subject's node document's top layer does not already contain subject, then add subject to subject's node document's top layer.Set the subject's previously focused element to the focused element.Run the dialog focusing steps for subject. The dialog focusing steps for a dialog element subject are as follows: Let control be the focus delegate of subject.If control is null, then set control to subject. Run the focusing steps for control. Let topDocument be the active document of control's node document's browsing context's top-level browsing context.If control's node document's origin is not the same as the origin of topDocument, then return.Empty topDocument's autofocus candidates.Set topDocument's autofocus processed flag to true. If at any time a dialog element is removed from a Document, then if that dialog is in that Document's top layer, it must be removed from it. Also, set the dialog element's is modal flag to false. When the close(returnValue) method is invoked, the user agent must close the dialog that the method was invoked on. If returnValue was given, it must be used as the return value; otherwise, there is no return value. When a dialog element subject is to be closed, optionally with a return value result, the user agent must run the following steps: If subject does not have an open attribute, then return.Remove subject's open attribute.Set the is modal flag of subject to false.If the argument result was provided, then set the returnValue attribute to the value of result.If subject is in its Document's top layer, then remove it. If subject's previously focused element is not null, then: Let element be subject's previously focused element.Set subject's previously focused element to null.Run the focusing steps for element; the viewport should not be scrolled by doing this step. Queue an element task on the user interaction task source given the subject element to fire an event named close at subject. The returnValue IDL attribute, on getting, must return the last value to which it was set. On setting, it must be set to the new value. When the element is created, it must be set to the empty string. We use show/close as the verbs for dialog elements, as opposed to verb pairs that are more commonly thought of as antonyms such as show/hide or open/close, due to the following constraints: Hiding a dialog is different from closing one. Closing a dialog gives it a return value, fires an event, unblocks the page for other dialogs, and so on. Whereas hiding a dialog is a purely visual property, and is something you can already do with the hidden attribute or by removing the open attribute. (See also the note above about removing the open attribute, and how hiding the dialog in that way is generally not desired.)Showing a dialog is different from opening one. Opening a dialog consists of creating and showing that dialog (similar to how window.open() both creates and shows a new window). Whereas showing the dialog is the process of taking a dialog element that is already in the DOM, and making it interactive and visible to the user.If we were to have a dialog.open() method despite the above, it would conflict with the dialog.open property. Furthermore, a survey of many other UI frameworks contemporary to the original design of the dialog element made it clear that the show/close verb pair was reasonably common. In summary, it turns out that the implications of certain verbs, and how they are used in technology contexts, mean that paired actions such as showing and closing a dialog are not always expressible as antonyms. Canceling dialogs: When Document is blocked by a modal dialog dialog, user agents may provide a user interface that, upon activation, queues an element task on the user interaction task source given the dialog element to run these steps: Let close be the result of firing an event named cancel at dialog, with the cancelable attribute initialized to true.If close is true and dialog has an open attribute, then close the dialog with no return value. Each dialog element has an is modal flag. When a dialog element is created, this flag must be set to false. Each dialog element has a previously focused element which is null or an element, and it is initially null. When showModal() and show() are called, this element is set to the currently focused element before running the dialog focusing steps. The open IDL attribute must reflect the open content attribute.

The div element has no special meaning at all. It represents its children. It can be used with the class, lang, and title attributes to mark up semantics common to a group of consecutive elements. It can also be used in a dl element, wrapping groups of dt and dd elements.

The dl element represents an association list consisting of zero or more name-value groups (a description list). A name-value group consists of one or more names (dt elements, possibly as children of a div element child) followed by one or more values (dd elements, possibly as children of a div element child), ignoring any nodes other than dt and dd element children, and dt and dd elements that are children of div element children. Within a single dl element, there should not be more than one dt element for each name. Name-value groups may be terms and definitions, metadata topics and values, questions and answers, or any other groups of name-value data. The values within a group are alternatives; multiple paragraphs forming part of the same value must all be given within the same dd element. The order of the list of groups, and of the names and values within each group, may be significant. In order to annotate groups with microdata attributes, or other global attributes that apply to whole groups, or just for styling purposes, each group in a dl element can be wrapped in a div element. This does not change the semantics of the dl element. The name-value groups of a dl element dl are determined using the following algorithm. A name-value group has a name (a list of dt elements, initially empty) and a value (a list of dd elements, initially empty). Let groups be an empty list of name-value groups.Let current be a new name-value group.Let seenDd be false.Let child be dl's first child.Let grandchild be null. While child is not null: If child is a div element, then: Let grandchild be child's first child. While grandchild is not null: Process dt or dd for grandchild.Set grandchild to grandchild's next sibling. Otherwise, process dt or dd for child.Set child to child's next sibling. If current is not empty, then append current to groups.Return groups. To process dt or dd for a node node means to follow these steps: Let groups, current, and seenDd be the same variables as those of the same name in the algorithm that invoked these steps. If node is a dt element, then: If seenDd is true, then append current to groups, set current to a new name-value group, and set seenDd to false.Append node to current's name. Otherwise, if node is a dd element, then append node to current's value and set seenDd to true.

The dt element represents the term, or name, part of a term-description group in a description list (dl element).

The em element represents stress emphasis of its contents. The level of stress that a particular piece of content has is given by its number of ancestor em elements. The placement of stress emphasis changes the meaning of the sentence. The element thus forms an integral part of the content. The precise way in which stress is used in this way depends on the language. The em element isn't a generic "italics" element. Sometimes, text is intended to stand out from the rest of the paragraph, as if it was in a different mood or voice. For this, the i element is more appropriate. The em element also isn't intended to convey importance; for that purpose, the strong element is more appropriate.

The embed element provides an integration point for an external (typically non-HTML) application or interactive content. The src attribute gives the URL of the resource being embedded. The attribute, if present, must contain a valid non-empty URL potentially surrounded by spaces. Authors should avoid referencing untrusted resources, as such a resource can be used to instantiate plugins or run scripts, even if the author has used features such as the Flash "allowScriptAccess" parameter. If the itemprop attribute is specified on an embed element, then the src attribute must also be specified. The type attribute, if present, gives the MIME type by which the plugin to instantiate is selected. The value must be a valid MIME type string. If both the type attribute and the src attribute are present, then the type attribute must specify the same type as the explicit Content-Type metadata of the resource given by the src attribute. While any of the following conditions are occurring, any plugin instantiated for the element must be removed, and the embed element represents nothing: The element has neither a src attribute nor a type attribute.The element has a media element ancestor.The element has an ancestor object element that is not showing its fallback content. An embed element is said to be potentially active when the following conditions are all met simultaneously: The element is in a document or was in a document the last time the event loop reached step 1.The element's node document is fully active.The element has either a src attribute set or a type attribute set (or both).The element's src attribute is either absent or its value is not the empty string.The element is not a descendant of a media element.The element is not a descendant of an object element that is not showing its fallback content.The element is being rendered, or was being rendered the last time the event loop reached step 1. Whenever an embed element that was not potentially active becomes potentially active, and whenever a potentially active embed element that is remaining potentially active and has its src attribute set, changed, or removed or its type attribute set, changed, or removed, the user agent must queue an element task on the embed task source given the element to run the embed element setup steps for that element. The embed element setup steps for a given embed element element are as follows: If another task has since been queued to run the embed element setup steps for element, then return. If element has a src attribute set, then: Let url be the result of parsing the value of element's src attribute, relative to element's node document.If url is failure, then return.Let request be a new request whose URL is url, client is element's node document's relevant settings object, destination is "embed", credentials mode is "include", mode is "navigate", and whose use-URL-credentials flag is set.Let processResponseEndOfBody given response res be to finalize and report timing with res, element's node document's relevant global object, and "embed". Fetch request, with processResponseEndOfBody set to processResponseEndOfBody, and processResponse set to the following steps given response response: If another task has since been queued to run the embed element setup steps for element, then return.If response is a network error, then fire an event named load at element, and return.Let type be the result of determining the type of content given element and response. Switch on type: null Display no plugin for element. image/svg+xml If element's nested browsing context is null, then create a new nested browsing context for element. Navigate element's nested browsing context to response, with historyHandling set to "replace" and the source browsing context set to element's node document's browsing context. element now represents its nested browsing context. Otherwise Display a plugin for element, given type and response. Fetching the resource must delay the load event of element's node document. Otherwise: Let type be the value of element's type attribute.If type is a type that a plugin supports, then display a plugin for element given type.Otherwise, display no plugin for element. To determine the type of the content given an embed element element and a response response, run the following steps: If element has a type attribute, and that attribute's value is a type that a plugin supports, then return the value of the type attribute. If the path component of response's url matches a pattern that a plugin supports, then return the type that that plugin can handle. For example, a plugin might say that it can handle URLs with path components that end with the four character string ".swf". If response has explicit Content-Type metadata, and that value is a type that a plugin supports, then return that value.Return null. To display a plugin for an embed element element, given a string type and optionally a response response: If element's nested browsing context is not null, then: Discard element's nested browsing context.Set element's nested browsing context to null. Find and instantiate an appropriate plugin based on type, replacing any previously-instantiated plugin for element. If response was given, forward it to the plugin.element now represents this plugin instance.Once the plugin, and response if given, are completely loaded, queue an element task on the DOM manipulation task source give element to fire an event named load at element. To display no plugin for an embed element element: If element's nested browsing context is not null, then: Discard element's nested browsing context.Set element's nested browsing context to null. Display an indication that no plugin could be found for element, replacing any previously-instantiated plugin for element.element now represents nothing. Whenever an embed element that was potentially active stops being potentially active, any plugin that had been instantiated for that element must be unloaded. When a plugin is to be instantiated but the sandboxed plugins browsing context flag is set on the embed element's node document's active sandboxing flag set, then the user agent must not instantiate the plugin, and must instead render the embed element in a manner that conveys that the plugin was disabled. The embed element potentially delays the load event. Any namespace-less attribute other than name, align, hspace, and vspace may be specified on the embed element, so long as its name is XML-compatible and contains no ASCII upper alphas. These attributes are then passed as parameters to the plugin. The user agent should pass the names and values of all the attributes of the embed element that have no namespace to the plugin used, when one is instantiated. The HTMLEmbedElement object representing the element must expose the scriptable interface of the plugin instantiated for the embed element, if any. The embed element supports dimension attributes. The IDL attributes src and type each must reflect the respective content attributes of the same name.

The fieldset element represents a set of form controls (or other content) grouped together, optionally with a caption. The caption is given by the first legend element that is a child of the fieldset element, if any. The remainder of the descendants form the group. The disabled attribute, when specified, causes all the form control descendants of the fieldset element, excluding those that are descendants of the fieldset element's first legend element child, if any, to be disabled. A fieldset element is a disabled fieldset if it matches any of the following conditions: Its disabled attribute is specified It is a descendant of another fieldset element whose disabled attribute is specified, and is not a descendant of that fieldset element's first legend element child, if any. The form attribute is used to explicitly associate the fieldset element with its form owner. The name attribute represents the element's name. The disabled IDL attribute must reflect the content attribute of the same name. The type IDL attribute must return the string "fieldset". The elements IDL attribute must return an HTMLCollection rooted at the fieldset element, whose filter matches listed elements. The willValidate, validity, and validationMessage attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The form and name IDL attributes are part of the element's forms API.

The figcaption element represents a caption or legend for the rest of the contents of the figcaption element's parent figure element, if any.

The figure element represents some flow content, optionally with a caption, that is self-contained (like a complete sentence) and is typically referenced as a single unit from the main flow of the document. The element can thus be used to annotate illustrations, diagrams, photos, code listings, etc. When a figure is referred to from the main content of the document by identifying it by its caption (e.g., by figure number), it enables such content to be easily moved away from that primary content, e.g., to the side of the page, to dedicated pages, or to an appendix, without affecting the flow of the document. If a figure element is referenced by its relative position, e.g., "in the photograph above" or "as the next figure shows", then moving the figure would disrupt the page's meaning. Authors are encouraged to consider using labels to refer to figures, rather than using such relative references, so that the page can easily be restyled without affecting the page's meaning. The first figcaption element child of the element, if any, represents the caption of the figure element's contents. If there is no child figcaption element, then there is no caption. A figure element's contents are part of the surrounding flow. If the purpose of the page is to display the figure, for example a photograph on an image sharing site, the figure and figcaption elements can be used to explicitly provide a caption for that figure. For content that is only tangentially related, or that serves a separate purpose than the surrounding flow, the aside element should be used (and can itself wrap a figure). For example, a pull quote that repeats content from an article would be more appropriate in an aside than in a figure, because it isn't part of the content, it's a repetition of the content for the purposes of enticing readers or highlighting key topics.

The footer element represents a footer for its nearest ancestor sectioning content element, or for the body element if there is no such ancestor. A footer typically contains information about its section such as who wrote it, links to related documents, copyright data, and the like. When the footer element contains entire sections, they represent appendices, indices, long colophons, verbose license agreements, and other such content. Footers don't necessarily have to appear at the end of a section, though they usually do. When there is no ancestor sectioning content element, then it applies to the whole page.

The form element represents a hyperlink that can be manipulated through a collection of form-associated elements, some of which can represent editable values that can be submitted to a server for processing. The accept-charset attribute gives the character encodings that are to be used for the submission. If specified, the value must be an ASCII case-insensitive match for "UTF-8". [ENCODING] The name attribute represents the form's name within the forms collection. The value must not be the empty string, and the value must be unique amongst the form elements in the forms collection that it is in, if any. The autocomplete attribute is an enumerated attribute. The attribute has two states. The on keyword maps to the on state, and the off keyword maps to the off state. The attribute may also be omitted. The missing value default and the invalid value default are the on state. The off state indicates that by default, form controls in the form will have their autofill field name set to "off"; the on state indicates that by default, form controls in the form will have their autofill field name set to "on". The action, enctype, method, novalidate, and target attributes are attributes for form submission. The rel attribute on form elements controls what kinds of links the elements create. The attribute's value must be a unordered set of unique space-separated tokens. The allowed keywords and their meanings are defined in an earlier section. rel's supported tokens are the keywords defined in HTML link types which are allowed on form elements, impact the processing model, and are supported by the user agent. The possible supported tokens are noreferrer, noopener, and opener. rel's supported tokens must only include the tokens from this list that the user agent implements the processing model for. The autocomplete IDL attribute must reflect the content attribute of the same name, limited to only known values. The name and rel IDL attributes must reflect the content attribute of the same name. The acceptCharset IDL attribute must reflect the accept-charset content attribute. The relList IDL attribute must reflect the rel content attribute. The elements IDL attribute must return an HTMLFormControlsCollection rooted at the form element's root, whose filter matches listed elements whose form owner is the form element, with the exception of input elements whose type attribute is in the Image Button state, which must, for historical reasons, be excluded from this particular collection. The length IDL attribute must return the number of nodes represented by the elements collection. The supported property indices at any instant are the indices supported by the object returned by the elements attribute at that instant. To determine the value of an indexed property for a form element, the user agent must return the value returned by the item method on the elements collection, when invoked with the given index as its argument. Each form element has a mapping of names to elements called the past names map. It is used to persist names of controls even when they change names. The supported property names consist of the names obtained from the following algorithm, in the order obtained from this algorithm: Let sourced names be an initially empty ordered list of tuples consisting of a string, an element, a source, where the source is either id, name, or past, and, if the source is past, an age. For each listed element candidate whose form owner is the form element, with the exception of any input elements whose type attribute is in the Image Button state: If candidate has an id attribute, add an entry to sourced names with that id attribute's value as the string, candidate as the element, and id as the source.If candidate has a name attribute, add an entry to sourced names with that name attribute's value as the string, candidate as the element, and name as the source. For each img element candidate whose form owner is the form element: If candidate has an id attribute, add an entry to sourced names with that id attribute's value as the string, candidate as the element, and id as the source.If candidate has a name attribute, add an entry to sourced names with that name attribute's value as the string, candidate as the element, and name as the source. For each entry past entry in the past names map add an entry to sourced names with the past entry's name as the string, past entry's element as the element, past as the source, and the length of time past entry has been in the past names map as the age. Sort sourced names by tree order of the element entry of each tuple, sorting entries with the same element by putting entries whose source is id first, then entries whose source is name, and finally entries whose source is past, and sorting entries with the same element and source by their age, oldest first.Remove any entries in sourced names that have the empty string as their name.Remove any entries in sourced names that have the same name as an earlier entry in the map.Return the list of names from sourced names, maintaining their relative order. To determine the value of a named property name for a form element, the user agent must run the following steps: Let candidates be a live RadioNodeList object containing all the listed elements, whose form owner is the form element, that have either an id attribute or a name attribute equal to name, with the exception of input elements whose type attribute is in the Image Button state, in tree order.If candidates is empty, let candidates be a live RadioNodeList object containing all the img elements, whose form owner is the form element, that have either an id attribute or a name attribute equal to name, in tree order.If candidates is empty, name is the name of one of the entries in the form element's past names map: return the object associated with name in that map.If candidates contains more than one node, return candidates.Otherwise, candidates contains exactly one node. Add a mapping from name to the node in candidates in the form element's past names map, replacing the previous entry with the same name, if any.Return the node in candidates. If an element listed in a form element's past names map changes form owner, then its entries must be removed from that map. The submit() method, when invoked, must submit the form element from the form element itself, with the submitted from submit() method flag set. The requestSubmit(submitter) method, when invoked, must run the following steps: If submitter is not null, then: If submitter is not a submit button, then throw a TypeError.If submitter's form owner is not this form element, then throw a "NotFoundError" DOMException. Otherwise, set submitter to this form element.Submit this form element, from submitter. The reset() method, when invoked, must run the following steps: If the form element is marked as locked for reset, then return.Mark the form element as locked for reset.Reset the form element.Unmark the form element as locked for reset. If the checkValidity() method is invoked, the user agent must statically validate the constraints of the form element, and return true if the constraint validation return a positive result, and false if it returned a negative result. If the reportValidity() method is invoked, the user agent must interactively validate the constraints of the form element, and return true if the constraint validation return a positive result, and false if it returned a negative result.

The head element represents a collection of metadata for the Document.

The header element represents a group of introductory or navigational aids.

The hgroup element represents a heading and related content. The element may be used to group an h1–h6 element with one or more p elements containing content representing a subheading, alternative title, or tagline.

The hr element represents a paragraph-level thematic break, e.g. a scene change in a story, or a transition to another topic within a section of a reference book.

The html element represents the root of an HTML document. Authors are encouraged to specify a lang attribute on the root html element, giving the document's language. This aids speech synthesis tools to determine what pronunciations to use, translation tools to determine what rules to use, and so forth.

The i element represents a span of text in an alternate voice or mood, or otherwise offset from the normal prose in a manner indicating a different quality of text, such as a taxonomic designation, a technical term, an idiomatic phrase from another language, transliteration, a thought, or a ship name in Western texts. Terms in languages different from the main text should be annotated with lang attributes (or, in XML, lang attributes in the XML namespace). Authors can use the class attribute on the i element to identify why the element is being used, so that if the style of a particular use (e.g. dream sequences as opposed to taxonomic terms) is to be changed at a later date, the author doesn't have to go through the entire document (or series of related documents) annotating each use. Authors are encouraged to consider whether other elements might be more applicable than the i element, for instance the em element for marking up stress emphasis, or the dfn element to mark up the defining instance of a term.

The iframe element represents its nested browsing context. The src attribute gives the URL of a page that the element's nested browsing context is to contain. The attribute, if present, must be a valid non-empty URL potentially surrounded by spaces. If the itemprop attribute is specified on an iframe element, then the src attribute must also be specified. The srcdoc attribute gives the content of the page that the element's nested browsing context is to contain. The value of the attribute is the source of an iframe srcdoc document. The srcdoc attribute, if present, must have a value using the HTML syntax that consists of the following syntactic components, in the given order: Any number of comments and ASCII whitespace.Optionally, a DOCTYPE. Any number of comments and ASCII whitespace.The document element, in the form of an html element.Any number of comments and ASCII whitespace. When an iframe element element is inserted into a document whose browsing context is non-null, the user agent must run these steps: Create a new nested browsing context for element.If element has a sandbox attribute, then parse the sandboxing directive given the attribute's value and element's iframe sandboxing flag set.Process the iframe attributes for element, with initialInsertion set to true. When an iframe element is removed from a document, the user agent must discard the element's nested browsing context, if it is not null, and then set the element's nested browsing context to null. Whenever an iframe element with a non-null nested browsing context has its srcdoc attribute set, changed, or removed, the user agent must process the iframe attributes. Similarly, whenever an iframe element with a non-null nested browsing context but with no srcdoc attribute specified has its src attribute set, changed, or removed, the user agent must process the iframe attributes. To process the iframe attributes for an element element, with an optional boolean initialInsertion (default false): If element's srcdoc attribute is specified, then: Set element's current navigation was lazy loaded boolean to false. If the will lazy load element steps given element return true, then: Set element's lazy load resumption steps to the rest of this algorithm starting with the step labeled navigate to the srcdoc resource.Set element's current navigation was lazy loaded boolean to true.Start intersection-observing a lazy loading element for element.Return. Navigate to the srcdoc resource: navigate an iframe or frame given element and a new response whose URL list is « about:srcdoc », header list is « (`Content-Type`, `text/html`) », and body is the value of element's srcdoc attribute. The resulting Document must be considered an iframe srcdoc document. Otherwise, run the shared attribute processing steps for iframe and frame elements given element and initialInsertion. The shared attribute processing steps for iframe and frame elements, given an element element and a boolean initialInsertion, are: Let url be the URL record about:blank.If element has a src attribute specified, and its value is not the empty string, then parse the value of that attribute relative to element's node document. If this is successful, then set url to the resulting URL record.If there exists an ancestor browsing context of element's nested browsing context whose active document's URL, ignoring fragments, is equal to url, then return. If url matches about:blank and initialInsertion is true, then: Perform the URL and history update steps given element's nested browsing context's active document and url. Run the iframe load event steps given element.Return. Let resource be a new request whose URL is url and whose referrer policy is the current state of element's referrerpolicy content attribute.If element is an iframe element, then set element's current navigation was lazy loaded boolean to false. If element is an iframe element, and the will lazy load element steps given element return true, then: Set element's lazy load resumption steps to the rest of this algorithm starting with the step labeled navigate to the resource.Set element's current navigation was lazy loaded boolean to true.Start intersection-observing a lazy loading element for element.Return. Navigate to the resource: navigate an iframe or frame given element and resource. To navigate an iframe or frame given an element element and a resource resource: Let historyHandling be "default". If element's nested browsing context's active document is not completely loaded, then set historyHandling to "replace".Let reportFrameTiming be the following step given response response: queue an element task on the networking task source given element's node document's relevant global object to finalize and report timing given response, element's node document's relevant global object, and element's local name.Navigate element's nested browsing context to resource, with historyHandling set to historyHandling, the source browsing context set to element's node document's browsing context, and processResponseEndOfBody set to reportFrameTiming. Each Document has an iframe load in progress flag and a mute iframe load flag. When a Document is created, these flags must be unset for that Document. To run the iframe load event steps, given an iframe element element: Assert: element's nested browsing context is not null.Let childDocument be the active document of element's nested browsing context.If childDocument has its mute iframe load flag set, then return.Set childDocument's iframe load in progress flag.Fire an event named load at element.Unset childDocument's iframe load in progress flag. This, in conjunction with scripting, can be used to probe the URL space of the local network's HTTP servers. User agents may implement cross-origin access control policies that are stricter than those described above to mitigate this attack, but unfortunately such policies are typically not compatible with existing web content. If an element type potentially delays the load event, then for each element element of that type, the user agent must delay the load event of element's node document if element's nested browsing context is non-null and any of the following are true: element's nested browsing context's active document is not ready for post-load tasks.Anything is delaying the load event of element's nested browsing context's active document.element's nested browsing context is in the delaying load events mode. Each iframe element has an associated current navigation was lazy loaded boolean, initially false. It is set and unset in the process the iframe attributes algorithm. An iframe element whose current navigation was lazy loaded boolean is false potentially delays the load event. The name attribute, if present, must be a valid browsing context name. The given value is used to name the element's nested browsing context if present when that is created. The sandbox attribute, when specified, enables a set of extra restrictions on any content hosted by the iframe. Its value must be an unordered set of unique space-separated tokens that are ASCII case-insensitive. The allowed values are: allow-downloadsallow-formsallow-modalsallow-orientation-lockallow-pointer-lockallow-popupsallow-popups-to-escape-sandboxallow-presentationallow-same-originallow-scriptsallow-top-navigationallow-top-navigation-by-user-activationallow-top-navigation-to-custom-protocols When the attribute is set, the content is treated as being from a unique origin, forms, scripts, and various potentially annoying APIs are disabled, links are prevented from targeting other browsing contexts, and plugins are secured. The allow-same-origin keyword causes the content to be treated as being from its real origin instead of forcing it into a unique origin; the allow-top-navigation keyword allows the content to navigate its top-level browsing context; the allow-top-navigation-by-user-activation keyword behaves similarly but allows such navigation only when the browsing context's active window has transient activation; the allow-top-navigation-to-custom-protocols reenables navigations toward non fetch scheme to be handed off to external software; and the allow-forms, allow-modals, allow-orientation-lock, allow-pointer-lock, allow-popups, allow-presentation, allow-scripts, and allow-popups-to-escape-sandbox keywords re-enable forms, modal dialogs, screen orientation lock, the pointer lock API, popups, the presentation API, scripts, and the creation of unsandboxed auxiliary browsing contexts respectively. The allow-downloads keyword allows content to perform downloads. [POINTERLOCK] [SCREENORIENTATION] [PRESENTATION] The allow-top-navigation and allow-top-navigation-by-user-activation keywords must not both be specified, as doing so is redundant; only allow-top-navigation will have an effect in such non-conformant markup. Similarly, the allow-top-navigation-to-custom-protocols keyword must not be specified if either allow-top-navigation or allow-popups are specified, as doing so is redundant. Setting both the allow-scripts and allow-same-origin keywords together when the embedded page has the same origin as the page containing the iframe allows the embedded page to simply remove the sandbox attribute and then reload itself, effectively breaking out of the sandbox altogether. These flags only take effect when the nested browsing context of the iframe element is navigated. Removing them, or removing the entire sandbox attribute, has no effect on an already-loaded page. Potentially hostile files should not be served from the same server as the file containing the iframe element. Sandboxing hostile content is of minimal help if an attacker can convince the user to just visit the hostile content directly, rather than in the iframe. To limit the damage that can be caused by hostile HTML content, it should be served from a separate dedicated domain. Using a different domain ensures that scripts in the files are unable to attack the site, even if the user is tricked into visiting those pages directly, without the protection of the sandbox attribute. When an iframe element's sandbox attribute is set or changed while it has a non-null nested browsing context, the user agent must parse the sandboxing directive given the attribute's value and the iframe element's iframe sandboxing flag set. When an iframe element's sandbox attribute is removed while it has a non-null nested browsing context, the user agent must empty the iframe element's iframe sandboxing flag set. The allow attribute, when specified, determines the container policy that will be used when the permissions policy for a Document in the iframe's nested browsing context is initialized. Its value must be a serialized permissions policy. [PERMISSIONSPOLICY] The allowfullscreen attribute is a boolean attribute. When specified, it indicates that Document objects in the iframe element's nested browsing context will be initialized with a permissions policy which allows the "fullscreen" feature to be used from any origin. This is enforced by the process permissions policy attributes algorithm. [PERMISSIONSPOLICY] To determine whether a Document object document is allowed to use the policy-controlled-feature feature, run these steps: If document's browsing context is null, then return false.If document's browsing context's active document is not document, then return false.If the result of running is feature enabled in document for origin on feature, document, and document's origin is "Enabled", then return true.Return false. Because they only influence the permissions policy of the nested browsing context's active document, the allow and allowfullscreen attributes only take effect when the nested browsing context of the iframe is navigated. Adding or removing them has no effect on an already-loaded document. The iframe element supports dimension attributes for cases where the embedded content has specific dimensions (e.g. ad units have well-defined dimensions). An iframe element never has fallback content, as it will always create a new nested browsing context, regardless of whether the specified initial contents are successfully used. The referrerpolicy attribute is a referrer policy attribute. Its purpose is to set the referrer policy used when processing the iframe attributes. [REFERRERPOLICY] The loading attribute is a lazy loading attribute. Its purpose is to indicate the policy for loading iframe elements that are outside the viewport. When the loading attribute's state is changed to the Eager state, the user agent must run these steps: Let resumptionSteps be the iframe element's lazy load resumption steps.If resumptionSteps is null, then return.Set the iframe's lazy load resumption steps to null.Invoke resumptionSteps. Descendants of iframe elements represent nothing. (In legacy user agents that do not support iframe elements, the contents would be parsed as markup that could act as fallback content.) The IDL attributes src, srcdoc, name, sandbox, and allow must reflect the respective content attributes of the same name. The supported tokens for sandbox's DOMTokenList are the allowed values defined in the sandbox attribute and supported by the user agent. The allowFullscreen IDL attribute must reflect the allowfullscreen content attribute. The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values. The loading IDL attribute must reflect the loading content attribute, limited to only known values. The contentDocument IDL attribute, on getting, must return the iframe element's content document. The contentWindow IDL attribute must return the WindowProxy object of the iframe element's nested browsing context, if its nested browsing context is non-null, or null otherwise.

An img element represents an image. An img element has a dimension attribute source, initially set to the element itself. The image given by the src and srcset attributes, and any previous sibling source elements' srcset attributes if the parent is a picture element, is the embedded content; the value of the alt attribute provides equivalent content for those who cannot process images or who have image loading disabled (i.e. it is the img element's fallback content). The requirements on the alt attribute's value are described in a separate section. The src attribute must be present, and must contain a valid non-empty URL potentially surrounded by spaces referencing a non-interactive, optionally animated, image resource that is neither paged nor scripted. The srcset attribute may also be present, and is a srcset attribute. The srcset attribute and the src attribute (if width descriptors are not used) contribute the image sources to the source set (if no source element was selected). If the srcset attribute is present and has any image candidate strings using a width descriptor, the sizes attribute must also be present, and is a sizes attribute. The sizes attribute contributes the source size to the source set (if no source element was selected). The crossorigin attribute is a CORS settings attribute. Its purpose is to allow images from third-party sites that allow cross-origin access to be used with canvas. The referrerpolicy attribute is a referrer policy attribute. Its purpose is to set the referrer policy used when fetching the image. [REFERRERPOLICY] The decoding attribute indicates the preferred method to decode this image. The attribute, if present, must be an image decoding hint. This attribute's missing value default and invalid value default are both the auto state. The loading attribute is a lazy loading attribute. Its purpose is to indicate the policy for loading images that are outside the viewport. When the loading attribute's state is changed to the Eager state, the user agent must run these steps: Let resumptionSteps be the img element's lazy load resumption steps.If resumptionSteps is null, then return.Set the img's lazy load resumption steps to null.Invoke resumptionSteps. The img HTML element insertion steps, given insertedNode, are: If insertedNode's parent is a picture element, then, count this as a relevant mutation for insertedNode. The img HTML element removing steps, given removedNode and oldParent, are: If oldParent is a picture element, then, count this as a relevant mutation for removedNode. The img element must not be used as a layout tool. In particular, img elements should not be used to display transparent images, as such images rarely convey meaning and rarely add anything useful to the document. What an img element represents depends on the src attribute and the alt attribute. If the src attribute is set and the alt attribute is set to the empty string The image is either decorative or supplemental to the rest of the content, redundant with some other information in the document. If the image is available and the user agent is configured to display that image, then the element represents the element's image data. Otherwise, the element represents nothing, and may be omitted completely from the rendering. User agents may provide the user with a notification that an image is present but has been omitted from the rendering. If the src attribute is set and the alt attribute is set to a value that isn't empty The image is a key part of the content; the alt attribute gives a textual equivalent or replacement for the image. If the image is available and the user agent is configured to display that image, then the element represents the element's image data. Otherwise, the element represents the text given by the alt attribute. User agents may provide the user with a notification that an image is present but has been omitted from the rendering. If the src attribute is set and the alt attribute is not The image might be a key part of the content, and there is no textual equivalent of the image available. If the image is available and the user agent is configured to display that image, then the element represents the element's image data. If the image has a src attribute whose value is the empty string, then the element represents nothing. Otherwise, the user agent should display some sort of indicator that there is an image that is not being rendered, and may, if requested by the user, or if so configured, or when required to provide contextual information in response to navigation, provide caption information for the image, derived as follows: If the image has a title attribute whose value is not the empty string, then return the value of that attribute.If the image is a descendant of a figure element that has a child figcaption element, and, ignoring the figcaption element and its descendants, the figure element has no flow content descendants other than inter-element whitespace and the img element, then return the contents of the first such figcaption element.Return nothing. (There is no caption information.) If the src attribute is not set and either the alt attribute is set to the empty string or the alt attribute is not set at all The element represents nothing. Otherwise The element represents the text given by the alt attribute. The alt attribute does not represent advisory information. User agents must not present the contents of the alt attribute in the same way as content of the title attribute. User agents may always provide the user with the option to display any image, or to prevent any image from being displayed. User agents may also apply heuristics to help the user make use of the image when the user is unable to see it, e.g. due to a visual disability or because they are using a text terminal with no graphics capabilities. Such heuristics could include, for instance, optical character recognition (OCR) of text found within the image. While user agents are encouraged to repair cases of missing alt attributes, authors must not rely on such behavior. Requirements for providing text to act as an alternative for images are described in detail below. The contents of img elements, if any, are ignored for the purposes of rendering. The usemap attribute, if present, can indicate that the image has an associated image map. The ismap attribute, when used on an element that is a descendant of an a element with an href attribute, indicates by its presence that the element provides access to a server-side image map. This affects how events are handled on the corresponding a element. The ismap attribute is a boolean attribute. The attribute must not be specified on an element that does not have an ancestor a element with an href attribute. The img element supports dimension attributes. The alt, src, srcset and sizes IDL attributes must reflect the respective content attributes of the same name. The crossOrigin IDL attribute must reflect the crossorigin content attribute, limited to only known values. The useMap IDL attribute must reflect the usemap content attribute. The isMap IDL attribute must reflect the ismap content attribute. The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values. The decoding IDL attribute must reflect the decoding content attribute, limited to only known values. The loading IDL attribute must reflect the loading content attribute, limited to only known values. The IDL attributes width and height must return the rendered width and height of the image, in CSS pixels, if the image is being rendered, and is being rendered to a visual medium; or else the density-corrected intrinsic width and height of the image, in CSS pixels, if the image has intrinsic dimensions and is available but not being rendered to a visual medium; or else 0, if the image is not available or does not have intrinsic dimensions. [CSS] On setting, they must act as if they reflected the respective content attributes of the same name. The IDL attributes naturalWidth and naturalHeight must return the density-corrected intrinsic width and height of the image, in CSS pixels, if the image has intrinsic dimensions and is available, or else 0. [CSS] The IDL attribute complete must return true if any of the following conditions is true: Both the src attribute and the srcset attribute are omitted. The srcset attribute is omitted and the src attribute's value is the empty string. The img element's current request's state is completely available and its pending request is null. The img element's current request's state is broken and its pending request is null. Otherwise, the attribute must return false. The currentSrc IDL attribute must return the img element's current request's current URL. The decode() method, when invoked, must perform the following steps: Let promise be a new promise. Queue a microtask to perform the following steps: This is done because updating the image data takes place in a microtask as well. Thus, to make code such as img.src = "stars.jpg"; img.decode(); properly decode stars.jpg, we need to delay any processing by one microtask. If any of the following conditions are true about this img element: its node document is not an active document;its current request's state is broken, then reject promise with an "EncodingError" DOMException. Otherwise, in parallel, wait for one of the following cases to occur, and perform the corresponding actions: This img element's node document stops being an active documentThis img element's current request changes or is mutatedThis img element's current request's state becomes broken Reject promise with an "EncodingError" DOMException. This img element's current request's state becomes completely available Decode the image. If decoding does not need to be performed for this image (for example because it is a vector graphic), resolve promise with undefined. If decoding fails (for example due to invalid image data), reject promise with an "EncodingError" DOMException. If the decoding process completes successfully, resolve promise with undefined. User agents should ensure that the decoded media data stays readily available until at least the end of the next successful update the rendering step in the event loop. This is an important part of the API contract, and should not be broken if at all possible. (Typically, this would only be violated in low-memory situations that require evicting decoded image data, or when the image is too large to keep in decoded form for this period of time.) Return promise. A legacy factory function is provided for creating HTMLImageElement objects (in addition to the factory methods from DOM such as createElement()): Image(width, height). When invoked, the legacy factory function must perform the following steps: Let document be the current global object's associated Document.Let img be the result of creating an element given document, img, and the HTML namespace.If width is given, then set an attribute value for img using "width" and width.If height is given, then set an attribute value for img using "height" and height.Return img.

The input element represents a typed data field, usually with a form control to allow the user to edit the data. The type attribute controls the data type (and associated control) of the element. It is an enumerated attribute. The following table lists the keywords and states for the attribute — the keywords in the left column map to the states in the cell in the second column on the same row as the keyword. Keyword State Data type Control type hidden Hidden An arbitrary string n/a text Text Text with no line breaks A text control search Search Text with no line breaks Search control tel Telephone Text with no line breaks A text control url URL An absolute URL A text control email Email An email address or list of email addresses A text control password Password Text with no line breaks (sensitive information) A text control that obscures data entry date Date A date (year, month, day) with no time zone A date control month Month A date consisting of a year and a month with no time zone A month control week Week A date consisting of a week-year number and a week number with no time zone A week control time Time A time (hour, minute, seconds, fractional seconds) with no time zone A time control datetime-local Local Date and Time A date and time (year, month, day, hour, minute, second, fraction of a second) with no time zone A date and time control number Number A numerical value A text control or spinner control range Range A numerical value, with the extra semantic that the exact value is not important A slider control or similar color Color An sRGB color with 8-bit red, green, and blue components A color picker checkbox Checkbox A set of zero or more values from a predefined list A checkbox radio Radio Button An enumerated value A radio button file File Upload Zero or more files each with a MIME type and optionally a filename A label and a button submit Submit Button An enumerated value, with the extra semantic that it must be the last value selected and initiates form submission A button image Image Button A coordinate, relative to a particular image's size, with the extra semantic that it must be the last value selected and initiates form submission Either a clickable image, or a button reset Reset Button n/a A button button Button n/a A button The missing value default and the invalid value default are the Text state. Which of the accept, alt, autocomplete, checked, dirname, formaction, formenctype, formmethod, formnovalidate, formtarget, height, list, max, maxlength, min, minlength, multiple, pattern, placeholder, readonly, required, size, src, step, and width content attributes, the checked, files, valueAsDate, valueAsNumber, and list IDL attributes, the select() method, the selectionStart, selectionEnd, and selectionDirection, IDL attributes, the setRangeText() and setSelectionRange() methods, the stepUp() and stepDown() methods, and the input and change events apply to an input element depends on the state of its type attribute. The subsections that define each type also clearly define in normative "bookkeeping" sections which of these feature apply, and which do not apply, to each type. The behavior of these features depends on whether they apply or not, as defined in their various sections (q.v. for content attributes, for APIs, for events). The following table is non-normative and summarizes which of those content attributes, IDL attributes, methods, and events apply to each state: Hidden Text, Search URL, Telephone Email Password Date, Month, Week, Time Local Date and Time Number Range Color Checkbox, Radio Button File Upload Submit Button Image Button Reset Button, Button Content attributes accept · · · · · · · · · · · Yes · · · alt · · · · · · · · · · · · · Yes · autocomplete Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes · · · · · checked · · · · · · · · · · Yes · · · · dirname · Yes · · · · · · · · · · · · · formaction · · · · · · · · · · · · Yes Yes · formenctype · · · · · · · · · · · · Yes Yes · formmethod · · · · · · · · · · · · Yes Yes · formnovalidate · · · · · · · · · · · · Yes Yes · formtarget · · · · · · · · · · · · Yes Yes · height · · · · · · · · · · · · · Yes · list · Yes Yes Yes · Yes Yes Yes Yes Yes · · · · · max · · · · · Yes Yes Yes Yes · · · · · · maxlength · Yes Yes Yes Yes · · · · · · · · · · min · · · · · Yes Yes Yes Yes · · · · · · minlength · Yes Yes Yes Yes · · · · · · · · · · multiple · · · Yes · · · · · · · Yes · · · pattern · Yes Yes Yes Yes · · · · · · · · · · placeholder · Yes Yes Yes Yes · · Yes · · · · · · · readonly · Yes Yes Yes Yes Yes Yes Yes · · · · · · · required · Yes Yes Yes Yes Yes Yes Yes · · Yes Yes · · · size · Yes Yes Yes Yes · · · · · · · · · · src · · · · · · · · · · · · · Yes · step · · · · · Yes Yes Yes Yes · · · · · · width · · · · · · · · · · · · · Yes · IDL attributes and methods checked · · · · · · · · · · Yes · · · · files · · · · · · · · · · · Yes · · · value default value value value value value value value value value default/on filename default default default valueAsDate · · · · · Yes · · · · · · · · · valueAsNumber · · · · · Yes Yes Yes Yes · · · · · · list · Yes Yes Yes · Yes Yes Yes Yes Yes · · · · · select() · Yes Yes Yes† Yes Yes† Yes† Yes† · Yes† · Yes† · · · selectionStart · Yes Yes · Yes · · · · · · · · · · selectionEnd · Yes Yes · Yes · · · · · · · · · · selectionDirection · Yes Yes · Yes · · · · · · · · · · setRangeText() · Yes Yes · Yes · · · · · · · · · · setSelectionRange() · Yes Yes · Yes · · · · · · · · · · stepDown() · · · · · Yes Yes Yes Yes · · · · · · stepUp() · · · · · Yes Yes Yes Yes · · · · · · Events input event · Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes · · · change event · Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes · · · † If the control has no selectable text, the select() method results in a no-op, with no "InvalidStateError" DOMException. Some states of the type attribute define a value sanitization algorithm. Each input element has a value, which is exposed by the value IDL attribute. Some states define an algorithm to convert a string to a number, an algorithm to convert a number to a string, an algorithm to convert a string to a Date object, and an algorithm to convert a Date object to a string, which are used by max, min, step, valueAsDate, valueAsNumber, and stepUp(). An input element's dirty value flag must be set to true whenever the user interacts with the control in a way that changes the value. (It is also set to true when the value is programmatically changed, as described in the definition of the value IDL attribute.) The value content attribute gives the default value of the input element. When the value content attribute is added, set, or removed, if the control's dirty value flag is false, the user agent must set the value of the element to the value of the value content attribute, if there is one, or the empty string otherwise, and then run the current value sanitization algorithm, if one is defined. Each input element has a checkedness, which is exposed by the checked IDL attribute. Each input element has a boolean dirty checkedness flag. When it is true, the element is said to have a dirty checkedness. The dirty checkedness flag must be initially set to false when the element is created, and must be set to true whenever the user interacts with the control in a way that changes the checkedness. The checked content attribute is a boolean attribute that gives the default checkedness of the input element. When the checked content attribute is added, if the control does not have dirty checkedness, the user agent must set the checkedness of the element to true; when the checked content attribute is removed, if the control does not have dirty checkedness, the user agent must set the checkedness of the element to false. The reset algorithm for input elements is to set the dirty value flag and dirty checkedness flag back to false, set the value of the element to the value of the value content attribute, if there is one, or the empty string otherwise, set the checkedness of the element to true if the element has a checked content attribute and false if it does not, empty the list of selected files, and then invoke the value sanitization algorithm, if the type attribute's current state defines one. Each input element can be mutable. Except where otherwise specified, an input element is always mutable. Similarly, except where otherwise specified, the user agent should not allow the user to modify the element's value or checkedness. When an input element is disabled, it is not mutable. The cloning steps for input elements must propagate the value, dirty value flag, checkedness, and dirty checkedness flag from the node being cloned to the copy. The activation behavior for input elements are these steps: If this element is not mutable and is not in the Checkbox state and is not in the Radio state, then return.Run this element's input activation behavior, if any, and do nothing otherwise. The legacy-pre-activation behavior for input elements are these steps: If this element's type attribute is in the Checkbox state, then set this element's checkedness to its opposite value (i.e. true if it is false, false if it is true) and set this element's indeterminate IDL attribute to false.If this element's type attribute is in the Radio Button state, then get a reference to the element in this element's radio button group that has its checkedness set to true, if any, and then set this element's checkedness to true. The legacy-canceled-activation behavior for input elements are these steps: If the element's type attribute is in the Checkbox state, then set the element's checkedness and the element's indeterminate IDL attribute back to the values they had before the legacy-pre-activation behavior was run.If this element's type attribute is in the Radio Button state, then if the element to which a reference was obtained in the legacy-pre-activation behavior, if any, is still in what is now this element's radio button group, if it still has one, and if so, setting that element's checkedness to true; or else, if there was no such element, or that element is no longer in this element's radio button group, or if this element no longer has a radio button group, setting this element's checkedness to false. When an input element is first created, the element's rendering and behavior must be set to the rendering and behavior defined for the type attribute's state, and the value sanitization algorithm, if one is defined for the type attribute's state, must be invoked. When an input element's type attribute changes state, the user agent must run the following steps: If the previous state of the element's type attribute put the value IDL attribute in the value mode, and the element's value is not the empty string, and the new state of the element's type attribute puts the value IDL attribute in either the default mode or the default/on mode, then set the element's value content attribute to the element's value.Otherwise, if the previous state of the element's type attribute put the value IDL attribute in any mode other than the value mode, and the new state of the element's type attribute puts the value IDL attribute in the value mode, then set the value of the element to the value of the value content attribute, if there is one, or the empty string otherwise, and then set the control's dirty value flag to false.Otherwise, if the previous state of the element's type attribute put the value IDL attribute in any mode other than the filename mode, and the new state of the element's type attribute puts the value IDL attribute in the filename mode, then set the value of the element to the empty string.Update the element's rendering and behavior to the new state's.Signal a type change for the element. (The Radio Button state uses this, in particular.)Invoke the value sanitization algorithm, if one is defined for the type attribute's new state.Let previouslySelectable be true if setRangeText() previously applied to the element, and false otherwise.Let nowSelectable be true if setRangeText() now applies to the element, and false otherwise.If previouslySelectable is false and nowSelectable is true, set the element's text entry cursor position to the beginning of the text control, and set its selection direction to "none". The name attribute represents the element's name. The dirname attribute controls how the element's directionality is submitted. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The form attribute is used to explicitly associate the input element with its form owner. The autocomplete attribute controls how the user agent provides autofill behavior. The indeterminate IDL attribute must initially be set to false. On getting, it must return the last value it was set to. On setting, it must be set to the new value. It has no effect except for changing the appearance of checkbox controls. The accept, alt, max, min, multiple, pattern, placeholder, required, size, src, and step IDL attributes must reflect the respective content attributes of the same name. The dirName IDL attribute must reflect the dirname content attribute. The readOnly IDL attribute must reflect the readonly content attribute. The defaultChecked IDL attribute must reflect the checked content attribute. The defaultValue IDL attribute must reflect the value content attribute. The type IDL attribute must reflect the respective content attribute of the same name, limited to only known values. The maxLength IDL attribute must reflect the maxlength content attribute, limited to only non-negative numbers. The minLength IDL attribute must reflect the minlength content attribute, limited to only non-negative numbers. The IDL attributes width and height must return the rendered width and height of the image, in CSS pixels, if an image is being rendered, and is being rendered to a visual medium; or else the intrinsic width and height of the image, in CSS pixels, if an image is available but not being rendered to a visual medium; or else 0, if no image is available. When the input element's type attribute is not in the Image Button state, then no image is available. [CSS] On setting, they must act as if they reflected the respective content attributes of the same name. The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The select(), selectionStart, selectionEnd, selectionDirection, setRangeText(), and setSelectionRange() methods and IDL attributes expose the element's text selection. The disabled, form, and name IDL attributes are part of the element's forms API.

The ins element represents an addition to the document. ins elements should not cross implied paragraph boundaries.

The kbd element represents user input (typically keyboard input, although it may also be used to represent other input, such as voice commands). When the kbd element is nested inside a samp element, it represents the input as it was echoed by the system. When the kbd element contains a samp element, it represents input based on system output, for example invoking a menu item. When the kbd element is nested inside another kbd element, it represents an actual key or other single unit of input as appropriate for the input mechanism.

The label element represents a caption in a user interface. The caption can be associated with a specific form control, known as the label element's labeled control, either using the for attribute, or by putting the form control inside the label element itself. Except where otherwise specified by the following rules, a label element has no labeled control. The for attribute may be specified to indicate a form control with which the caption is to be associated. If the attribute is specified, the attribute's value must be the ID of a labelable element in the same tree as the label element. If the attribute is specified and there is an element in the tree whose ID is equal to the value of the for attribute, and the first such element in tree order is a labelable element, then that element is the label element's labeled control. If the for attribute is not specified, but the label element has a labelable element descendant, then the first such descendant in tree order is the label element's labeled control. The label element's exact default presentation and behavior, in particular what its activation behavior might be, if anything, should match the platform's label behavior. The activation behavior of a label element for events targeted at interactive content descendants of a label element, and any descendants of those interactive content descendants, must be to do nothing. The htmlFor IDL attribute must reflect the for content attribute. The control IDL attribute must return the label element's labeled control, if any, or null if there isn't one. The form IDL attribute must run the following steps: If the label element has no labeled control, then return null.If the label element's labeled control is not a form-associated element, then return null.Return the label element's labeled control's form owner (which can still be null). Labelable elements and all input elements have a live NodeList object associated with them that represents the list of label elements, in tree order, whose labeled control is the element in question. The labels IDL attribute of labelable elements that are not form-associated custom elements, and the labels IDL attribute of input elements, on getting, must return that NodeList object, and that same value must always be returned, unless this element is an input element whose type attribute is in the Hidden state, in which case it must instead return null. Form-associated custom elements don't have a labels IDL attribute. Instead, their ElementInternals object has a labels IDL attribute. On getting, it must throw a "NotSupportedError" DOMException if the target element is not a form-associated custom element. Otherwise, it must return that NodeList object, and that same value must always be returned.

The legend element represents a caption for the rest of the contents of the legend element's parent fieldset element, if any. The form IDL attribute's behavior depends on whether the legend element is in a fieldset element or not. If the legend has a fieldset element as its parent, then the form IDL attribute must return the same value as the form IDL attribute on that fieldset element. Otherwise, it must return null.

The li element represents a list item. If its parent element is an ol, ul, or menu element, then the element is an item of the parent element's list, as defined for those elements. Otherwise, the list item has no defined list-related relationship to any other li element. The value attribute, if present, must be a valid integer. It is used to determine the ordinal value of the list item, when the li's list owner is an ol element. Any element whose computed value of 'display' is 'list-item' has a list owner, which is determined as follows: If the element is not being rendered, return null; the element has no list owner. Let ancestor be the element's parent.If the element has an ol, ul, or menu ancestor, set ancestor to the closest such ancestor element. Return the closest inclusive ancestor of ancestor that produces a CSS box. To determine the ordinal value of each element owned by a given list owner owner, perform the following steps: Let i be 1.If owner is an ol element, let numbering be owner's starting value. Otherwise, let numbering be 1.Loop: If i is greater than the number of list items that owner owns, then return; all of owner's owned list items have been assigned ordinal values.Let item be the ith of owner's owned list items, in tree order. If item is an li element that has a value attribute, then: Let parsed be the result of parsing the value of the attribute as an integer.If parsed is not an error, then set numbering to parsed. The ordinal value of item is numbering.If owner is an ol element, and owner has a reversed attribute, decrement numbering by 1; otherwise, increment numbering by 1.Increment i by 1.Go to the step labeled loop. The value IDL attribute must reflect the value of the value content attribute.

The link element allows authors to link their document to other resources. The address of the link(s) is given by the href attribute. If the href attribute is present, then its value must be a valid non-empty URL potentially surrounded by spaces. One or both of the href or imagesrcset attributes must be present. If both the href and imagesrcset attributes are absent, then the element does not define a link. The types of link indicated (the relationships) are given by the value of the rel attribute, which, if present, must have a value that is a unordered set of unique space-separated tokens. The allowed keywords and their meanings are defined in a later section. If the rel attribute is absent, has no keywords, or if none of the keywords used are allowed according to the definitions in this specification, then the element does not create any links. rel's supported tokens are the keywords defined in HTML link types which are allowed on link elements, impact the processing model, and are supported by the user agent. The possible supported tokens are alternate, dns-prefetch, icon, manifest, modulepreload, next, pingback, preconnect, prefetch, preload, prerender, search, and stylesheet. rel's supported tokens must only include the tokens from this list that the user agent implements the processing model for. A link element must have either a rel attribute or an itemprop attribute, but not both. If a link element has an itemprop attribute, or has a rel attribute that contains only keywords that are body-ok, then the element is said to be allowed in the body. This means that the element can be used where phrasing content is expected. Two categories of links can be created using the link element: links to external resources and hyperlinks. The link types section defines whether a particular link type is an external resource or a hyperlink. One link element can create multiple links (of which some might be external resource links and some might be hyperlinks); exactly which and how many links are created depends on the keywords given in the rel attribute. User agents must process the links on a per-link basis, not a per-element basis. Hyperlinks created with the link element and its rel attribute apply to the whole document. This contrasts with the rel attribute of a and area elements, which indicates the type of a link whose context is given by the link's location within the document. Unlike those created by a and area elements, hyperlinks created by link elements are not displayed as part of the document by default, in user agents that support the suggested default rendering. And even if they are force-displayed using CSS, they have no activation behavior. Instead, they primarily provide semantic information which might be used by the page or by other software that consumes the page's contents. Additionally, the user agent can provide its own UI for following such hyperlinks. The exact behavior for links to external resources depends on the exact relationship, as defined for the relevant link type. The crossorigin attribute is a CORS settings attribute. It is intended for use with external resource links. The media attribute says which media the resource applies to. The value must be a valid media query list. The integrity attribute represents the integrity metadata for requests which this element is responsible for. The value is text. The attribute must only be specified on link elements that have a rel attribute that contains the stylesheet, preload, or modulepreload keyword. [SRI] The hreflang attribute on the link element has the same semantics as the hreflang attribute on the a element. The type attribute gives the MIME type of the linked resource. It is purely advisory. The value must be a valid MIME type string. For external resource links, the type attribute is used as a hint to user agents so that they can avoid fetching resources they do not support. The referrerpolicy attribute is a referrer policy attribute. It is intended for use with external resource links, where it helps set the referrer policy used when fetching and processing the linked resource. [REFERRERPOLICY]. The title attribute gives the title of the link. With one exception, it is purely advisory. The value is text. The exception is for style sheet links that are in a document tree, for which the title attribute defines CSS style sheet sets. The imagesrcset attribute may be present, and is a srcset attribute. The imagesrcset and href attributes (if width descriptors are not used) together contribute the image sources to the source set. If the imagesrcset attribute is present and has any image candidate strings using a width descriptor, the imagesizes attribute must also be present, and is a sizes attribute. The imagesizes attribute contributes the source size to the source set. The imagesrcset and imagesizes attributes must only be specified on link elements that have both a rel attribute that specifies the preload keyword, as well as an as attribute in the "image" state. The sizes attribute gives the sizes of icons for visual media. Its value, if present, is merely advisory. User agents may use the value to decide which icon(s) to use if multiple icons are available. If specified, the attribute must have a value that is an unordered set of unique space-separated tokens which are ASCII case-insensitive. Each value must be either an ASCII case-insensitive match for the string "any", or a value that consists of two valid non-negative integers that do not have a leading U+0030 DIGIT ZERO (0) character and that are separated by a single U+0078 LATIN SMALL LETTER X or U+0058 LATIN CAPITAL LETTER X character. The attribute must only be specified on link elements that have a rel attribute that specifies the icon keyword or the apple-touch-icon keyword. The as attribute specifies the potential destination for a preload request for the resource given by the href attribute. It is an enumerated attribute. Each potential destination is a keyword for this attribute, mapping to a state of the same name. The attribute must be specified on link elements that have a rel attribute that contains the preload keyword. It may be specified on link elements that have a rel attribute that contains the modulepreload keyword; in such cases it must have a value which is a script-like destination. For other link elements, it must not be specified. The processing model for how the as attribute is used is given in an individual link type's fetch and process the linked resource algorithm. The blocking attribute is a blocking attribute. It is used by link types modulepreload, preload and stylesheet, and it must only be specified on link elements that have a rel attribute containing one of those keywords. The color attribute is used with the mask-icon link type. The attribute must only be specified on link elements that have a rel attribute that contains the mask-icon keyword. The value must be a string that matches the CSS production, defining a suggested color that user agents can use to customize the display of the icon that the user sees when they pin your site. link elements have an associated explicitly enabled boolean. It is initially false. The disabled attribute is a boolean attribute that is used with the stylesheet link type. The attribute must only be specified on link elements that have a rel attribute that contains the stylesheet keyword. Whenever the disabled attribute is removed, set the link element's explicitly enabled attribute to true. The IDL attributes href, hreflang, integrity, media, rel, sizes, type, blocking and disabled each must reflect the respective content attributes of the same name. The as IDL attribute must reflect the as content attribute, limited to only known values. The crossOrigin IDL attribute must reflect the crossorigin content attribute, limited to only known values. The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values. The imageSrcset IDL attribute must reflect the imagesrcset content attribute. The imageSizes IDL attribute must reflect the imagesizes content attribute. The relList IDL attribute must reflect the rel content attribute.

The main element represents the dominant contents of the document. A document must not have more than one main element that does not have the hidden attribute specified. A hierarchically correct main element is one whose ancestor elements are limited to html, body, div, form without an accessible name, and autonomous custom elements. Each main element must be a hierarchically correct main element.

The map element, in conjunction with an img element and any area element descendants, defines an image map. The element represents its children. The name attribute gives the map a name so that it can be referenced. The attribute must be present and must have a non-empty value with no ASCII whitespace. The value of the name attribute must not be equal to the value of the name attribute of another map element in the same tree. If the id attribute is also specified, both attributes must have the same value. The areas attribute must return an HTMLCollection rooted at the map element, whose filter matches only area elements. The IDL attribute name must reflect the content attribute of the same name.

The mark element represents a run of text in one document marked or highlighted for reference purposes, due to its relevance in another context. When used in a quotation or other block of text referred to from the prose, it indicates a highlight that was not originally present but which has been added to bring the reader's attention to a part of the text that might not have been considered important by the original author when the block was originally written, but which is now under previously unexpected scrutiny. When used in the main prose of a document, it indicates a part of the document that has been highlighted due to its likely relevance to the user's current activity.

The menu element represents a toolbar consisting of its contents, in the form of an unordered list of items (represented by li elements), each of which represents a command that the user can perform or activate.

The meta element represents various kinds of metadata that cannot be expressed using the title, base, link, style, and script elements. The meta element can represent document-level metadata with the name attribute, pragma directives with the http-equiv attribute, and the file's character encoding declaration when an HTML document is serialized to string form (e.g. for transmission over the network or for disk storage) with the charset attribute. Exactly one of the name, http-equiv, charset, and itemprop attributes must be specified. If either name, http-equiv, or itemprop is specified, then the content attribute must also be specified. Otherwise, it must be omitted. The charset attribute specifies the character encoding used by the document. This is a character encoding declaration. If the attribute is present, its value must be an ASCII case-insensitive match for the string "utf-8". There must not be more than one meta element with a charset attribute per document. The content attribute gives the value of the document metadata or pragma directive when the element is used for those purposes. The allowed values depend on the exact context, as described in subsequent sections of this specification. If a meta element has a name attribute, it sets document metadata. Document metadata is expressed in terms of name-value pairs, the name attribute on the meta element giving the name, and the content attribute on the same element giving the value. The name specifies what aspect of metadata is being set; valid names and the meaning of their values are described in the following sections. If a meta element has no content attribute, then the value part of the metadata name-value pair is the empty string. The media attribute says which media the metadata applies to. The value must be a valid media query list. Unless the name is theme-color, the media attribute has no effect on the processing model and must not be used by authors. The name, content, and media IDL attributes must reflect the respective content attributes of the same name. The IDL attribute httpEquiv must reflect the content attribute http-equiv.

The meter element represents a scalar measurement within a known range, or a fractional value; for example disk usage, the relevance of a query result, or the fraction of a voting population to have selected a particular candidate. This is also known as a gauge. The meter element should not be used to indicate progress (as in a progress bar). For that role, HTML provides a separate progress element. There are six attributes that determine the semantics of the gauge represented by the element. The min attribute specifies the lower bound of the range, and the max attribute specifies the upper bound. The value attribute specifies the value to have the gauge indicate as the "measured" value. The other three attributes can be used to segment the gauge's range into "low", "medium", and "high" parts, and to indicate which part of the gauge is the "optimum" part. The low attribute specifies the range that is considered to be the "low" part, and the high attribute specifies the range that is considered to be the "high" part. The optimum attribute gives the position that is "optimum"; if that is higher than the "high" value then this indicates that the higher the value, the better; if it's lower than the "low" mark then it indicates that lower values are better, and naturally if it is in between then it indicates that neither high nor low values are good. Authoring requirements: The value attribute must be specified. The value, min, low, high, max, and optimum attributes, when present, must have values that are valid floating-point numbers. In addition, the attributes' values are further constrained: Let value be the value attribute's number. If the min attribute is specified, then let minimum be that attribute's value; otherwise, let it be zero. If the max attribute is specified, then let maximum be that attribute's value; otherwise, let it be 1.0. The following inequalities must hold, as applicable: minimum ≤ value ≤ maximumminimum ≤ low ≤ maximum (if low is specified)minimum ≤ high ≤ maximum (if high is specified)minimum ≤ optimum ≤ maximum (if optimum is specified)low ≤ high (if both low and high are specified) Authors are encouraged to include a textual representation of the gauge's state in the element's contents, for users of user agents that do not support the meter element. When used with microdata, the meter element's value attribute provides the element's machine-readable value. There is no explicit way to specify units in the meter element, but the units may be specified in the title attribute in free-form text. User agent requirements: User agents must parse the min, max, value, low, high, and optimum attributes using the rules for parsing floating-point number values. User agents must then use all these numbers to obtain values for six points on the gauge, as follows. (The order in which these are evaluated is important, as some of the values refer to earlier ones.) The minimum value If the min attribute is specified and a value could be parsed out of it, then the minimum value is that value. Otherwise, the minimum value is zero. The maximum value If the max attribute is specified and a value could be parsed out of it, then the candidate maximum value is that value. Otherwise, the candidate maximum value is 1.0. If the candidate maximum value is greater than or equal to the minimum value, then the maximum value is the candidate maximum value. Otherwise, the maximum value is the same as the minimum value. The actual value If the value attribute is specified and a value could be parsed out of it, then that value is the candidate actual value. Otherwise, the candidate actual value is zero. If the candidate actual value is less than the minimum value, then the actual value is the minimum value. Otherwise, if the candidate actual value is greater than the maximum value, then the actual value is the maximum value. Otherwise, the actual value is the candidate actual value. The low boundary If the low attribute is specified and a value could be parsed out of it, then the candidate low boundary is that value. Otherwise, the candidate low boundary is the same as the minimum value. If the candidate low boundary is less than the minimum value, then the low boundary is the minimum value. Otherwise, if the candidate low boundary is greater than the maximum value, then the low boundary is the maximum value. Otherwise, the low boundary is the candidate low boundary. The high boundary If the high attribute is specified and a value could be parsed out of it, then the candidate high boundary is that value. Otherwise, the candidate high boundary is the same as the maximum value. If the candidate high boundary is less than the low boundary, then the high boundary is the low boundary. Otherwise, if the candidate high boundary is greater than the maximum value, then the high boundary is the maximum value. Otherwise, the high boundary is the candidate high boundary. The optimum point If the optimum attribute is specified and a value could be parsed out of it, then the candidate optimum point is that value. Otherwise, the candidate optimum point is the midpoint between the minimum value and the maximum value. If the candidate optimum point is less than the minimum value, then the optimum point is the minimum value. Otherwise, if the candidate optimum point is greater than the maximum value, then the optimum point is the maximum value. Otherwise, the optimum point is the candidate optimum point. All of which will result in the following inequalities all being true: minimum value ≤ actual value ≤ maximum valueminimum value ≤ low boundary ≤ high boundary ≤ maximum valueminimum value ≤ optimum point ≤ maximum value UA requirements for regions of the gauge: If the optimum point is equal to the low boundary or the high boundary, or anywhere in between them, then the region between the low and high boundaries of the gauge must be treated as the optimum region, and the low and high parts, if any, must be treated as suboptimal. Otherwise, if the optimum point is less than the low boundary, then the region between the minimum value and the low boundary must be treated as the optimum region, the region from the low boundary up to the high boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region. Finally, if the optimum point is higher than the high boundary, then the situation is reversed; the region between the high boundary and the maximum value must be treated as the optimum region, the region from the high boundary down to the low boundary must be treated as a suboptimal region, and the remaining region must be treated as an even less good region. UA requirements for showing the gauge: When representing a meter element to the user, the UA should indicate the relative position of the actual value to the minimum and maximum values, and the relationship between the actual value and the three regions of the gauge. User agents may combine the value of the title attribute and the other attributes to provide context-sensitive help or inline text detailing the actual values. The value IDL attribute, on getting, must return the actual value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the value content attribute must be set to that string. The min IDL attribute, on getting, must return the minimum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the min content attribute must be set to that string. The max IDL attribute, on getting, must return the maximum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the max content attribute must be set to that string. The low IDL attribute, on getting, must return the low boundary. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the low content attribute must be set to that string. The high IDL attribute, on getting, must return the high boundary. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the high content attribute must be set to that string. The optimum IDL attribute, on getting, must return the optimum value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the optimum content attribute must be set to that string. The labels IDL attribute provides a list of the element's labels.

The nav element represents a section of a page that links to other pages or to parts within the page: a section with navigation links.

The noscript element represents nothing if scripting is enabled, and represents its children if scripting is disabled. It is used to present different markup to user agents that support scripting and those that don't support scripting, by affecting how the document is parsed. When used in HTML documents, the allowed content model is as follows: In a head element, if scripting is disabled for the noscript elementThe noscript element must contain only link, style, and meta elements.In a head element, if scripting is enabled for the noscript elementThe noscript element must contain only text, except that invoking the HTML fragment parsing algorithm with the noscript element as the context element and the text contents as the input must result in a list of nodes that consists only of link, style, and meta elements that would be conforming if they were children of the noscript element, and no parse errors.Outside of head elements, if scripting is disabled for the noscript elementThe noscript element's content model is transparent, with the additional restriction that a noscript element must not have a noscript element as an ancestor (that is, noscript can't be nested).Outside of head elements, if scripting is enabled for the noscript element The noscript element must contain only text, except that the text must be such that running the following algorithm results in a conforming document with no noscript elements and no script elements, and such that no step in the algorithm throws an exception or causes an HTML parser to flag a parse error: Remove every script element from the document.Make a list of every noscript element in the document. For every noscript element in that list, perform the following steps: Let s be the child text content of the noscript element.Set the outerHTML attribute of the noscript element to the value of s. (This, as a side-effect, causes the noscript element to be removed from the document.) [DOMPARSING] The noscript element must not be used in XML documents. The noscript element has no other requirements. In particular, children of the noscript element are not exempt from form submission, scripting, and so forth, even when scripting is enabled for the element.

The object element can represent an external resource, which, depending on the type of the resource, will either be treated as an image, as a child browsing context, or as an external resource to be processed by a plugin. The data attribute specifies the URL of the resource. It must be present, and must contain a valid non-empty URL potentially surrounded by spaces. Authors should avoid referencing untrusted resources, as such a resource can be used to instantiate plugins or run scripts, even if the author has used features such as the Flash "allowScriptAccess" parameter. The type attribute, if present, specifies the type of the resource. If present, the attribute must be a valid MIME type string. The name attribute, if present, must be a valid browsing context name. The given value is used to name the element's nested browsing context, if applicable, and if present when the element's nested browsing context is created. Whenever one of the following conditions occur: the element is created, the element is popped off the stack of open elements of an HTML parser or XML parser, the element is not on the stack of open elements of an HTML parser or XML parser, and it is either inserted into a document or removed from a document, the element's node document changes whether it is fully active, one of the element's ancestor object elements changes to or from showing its fallback content, the element's classid attribute is set, changed, or removed, the element's classid attribute is not present, and its data attribute is set, changed, or removed, neither the element's classid attribute nor its data attribute are present, and its type attribute is set, changed, or removed, the element changes from being rendered to not being rendered, or vice versa, ...the user agent must queue an element task on the DOM manipulation task source given the object element to run the following steps to (re)determine what the object element represents. This task being queued or actively running must delay the load event of the element's node document. If the user has indicated a preference that this object element's fallback content be shown instead of the element's usual behavior, then jump to the step below labeled fallback. If the element has an ancestor media element, or has an ancestor object element that is not showing its fallback content, or if the element is not in a document whose browsing context is non-null, or if the element's node document is not fully active, or if the element is still in the stack of open elements of an HTML parser or XML parser, or if the element is not being rendered, then jump to the step below labeled fallback. If the classid attribute is present, and has a value that isn't the empty string, then: if the user agent can find a plugin suitable according to the value of the classid attribute, and plugins aren't being sandboxed, then that plugin should be used, and the value of the data attribute, if any, should be passed to the plugin. If no suitable plugin can be found, or if the plugin reports an error, jump to the step below labeled fallback. If the data attribute is present and its value is not the empty string, then: If the type attribute is present and its value is not a type that the user agent supports, and is not a type that the user agent can find a plugin for, then the user agent may jump to the step below labeled fallback without fetching the content to examine its real type.Parse a URL given the data attribute, relative to the element's node document.If that failed, fire an event named error at the element, then jump to the step below labeled fallback.Let request be a new request whose URL is the resulting URL record, client is the element's node document's relevant settings object, destination is "object", credentials mode is "include", mode is "navigate", and whose use-URL-credentials flag is set. Fetch request, with processResponseEndOfBody given response res set to finalize and report timing with res, the element's node document's relevant global object, and "object". Fetching the resource must delay the load event of the element's node document until the task that is queued by the networking task source once the resource has been fetched (defined next) has been run. If the resource is not yet available (e.g. because the resource was not available in the cache, so that loading the resource required making a request over the network), then jump to the step below labeled fallback. The task that is queued by the networking task source once the resource is available must restart this algorithm from this step. Resources can load incrementally; user agents may opt to consider a resource "available" whenever enough data has been obtained to begin processing the resource.If the load failed (e.g. there was an HTTP 404 error, there was a DNS error), fire an event named error at the element, then jump to the step below labeled fallback. Determine the resource type, as follows: Let the resource type be unknown. If the user agent is configured to strictly obey Content-Type headers for this resource, and the resource has associated Content-Type metadata, then let the resource type be the type specified in the resource's Content-Type metadata, and jump to the step below labeled handler. This can introduce a vulnerability, wherein a site is trying to embed a resource that uses a particular plugin, but the remote site overrides that and instead furnishes the user agent with a resource that triggers a different plugin with different security characteristics. If there is a type attribute present on the object element, and that attribute's value is not a type that the user agent supports, but it is a type that a plugin supports, then let the resource type be the type specified in that type attribute, and jump to the step below labeled handler. Run the appropriate set of steps from the following list: If the resource has associated Content-Type metadata Let binary be false. If the type specified in the resource's Content-Type metadata is "text/plain", and the result of applying the rules for distinguishing if a resource is text or binary to the resource is that the resource is not text/plain, then set binary to true. If the type specified in the resource's Content-Type metadata is "application/octet-stream", then set binary to true. If binary is false, then let the resource type be the type specified in the resource's Content-Type metadata, and jump to the step below labeled handler. If there is a type attribute present on the object element, and its value is not application/octet-stream, then run the following steps: If the attribute's value is a type that a plugin supports, or the attribute's value is a type that starts with "image/" that is not also an XML MIME type, then let the resource type be the type specified in that type attribute. Jump to the step below labeled handler. Otherwise, if the resource does not have associated Content-Type metadata If there is a type attribute present on the object element, then let the tentative type be the type specified in that type attribute. Otherwise, let tentative type be the computed type of the resource. If tentative type is not application/octet-stream, then let resource type be tentative type and jump to the step below labeled handler. If applying the URL parser algorithm to the URL of the specified resource (after any redirects) results in a URL record whose path component matches a pattern that a plugin supports, then let resource type be the type that that plugin can handle. For example, a plugin might say that it can handle resources with path components that end with the four character string ".swf". Handler: Handle the content as given by the first of the following cases that matches: If the resource type is not a type that the user agent supports, but it is a type that a plugin supports If the object element's nested browsing context is non-null, then it must be discarded and then set to null. If plugins are being sandboxed, then jump to the step below labeled fallback. Otherwise, the user agent should use the plugin that supports resource type and pass the content of the resource to that plugin. If the plugin reports an error, then jump to the step below labeled fallback. If the resource type is an XML MIME type, or if the resource type does not start with "image/" If the object element's nested browsing context is null, then create a new nested browsing context for the element. If the URL of the given resource does not match about:blank, then navigate the element's nested browsing context to that resource, with historyHandling set to "replace" and the source browsing context set to the object element's node document's browsing context. (The data attribute of the object element doesn't get updated if the browsing context gets further navigated to other locations.) The object element represents its nested browsing context. If the resource type starts with "image/", and support for images has not been disabled If the object element's nested browsing context is non-null, then it must be discarded and then set to null. Apply the image sniffing rules to determine the type of the image. The object element represents the specified image. If the image cannot be rendered, e.g. because it is malformed or in an unsupported format, jump to the step below labeled fallback. Otherwise The given resource type is not supported. Jump to the step below labeled fallback. The element's contents are not part of what the object element represents. If the object element does not represent its nested browsing context, then once the resource is completely loaded, queue an element task on the DOM manipulation task source given the object element to fire an event named load at the element. Return. If the data attribute is absent but the type attribute is present, and the user agent can find a plugin suitable according to the value of the type attribute, and plugins aren't being sandboxed, then that plugin should be used. If these conditions cannot be met, or if the plugin reports an error, jump to the step below labeled fallback. Otherwise return; once the plugin is completely loaded, queue an element task on the DOM manipulation task source given the object element to fire an event named load at the element.Fallback: The object element represents the element's children. This is the element's fallback content. If the element has an instantiated plugin, then unload it. If the element's nested browsing context is non-null, then it must be discarded and then set to null. When the algorithm above instantiates a plugin, the user agent should pass to the plugin used the names and values of all the attributes on the element, in the order they were added to the element, with the attributes added by the parser being ordered in source order. If the plugin supports a scriptable interface, the HTMLObjectElement object representing the element should expose that interface. The object element represents the plugin. The plugin is not a nested browsing context. Plugins are considered sandboxed for the purpose of an object element if the sandboxed plugins browsing context flag is set on the object element's node document's active sandboxing flag set. Due to the algorithm above, the contents of object elements act as fallback content, used only when referenced resources can't be shown (e.g. because it returned a 404 error). This allows multiple object elements to be nested inside each other, targeting multiple user agents with different capabilities, with the user agent picking the first one it supports. The object element potentially delays the load event. The form attribute is used to explicitly associate the object element with its form owner. The object element supports dimension attributes. The IDL attributes data, type, and name each must reflect the respective content attributes of the same name. The contentDocument IDL attribute, on getting, must return the object element's content document. The contentWindow IDL attribute must return the WindowProxy object of the object element's nested browsing context, if its nested browsing context is non-null; otherwise, it must return null. The willValidate, validity, and validationMessage attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The form IDL attribute is part of the element's forms API.

The ol element represents a list of items, where the items have been intentionally ordered, such that changing the order would change the meaning of the document. The items of the list are the li element child nodes of the ol element, in tree order. The reversed attribute is a boolean attribute. If present, it indicates that the list is a descending list (..., 3, 2, 1). If the attribute is omitted, the list is an ascending list (1, 2, 3, ...). The start attribute, if present, must be a valid integer. It is used to determine the starting value of the list. An ol element has a starting value, which is an integer determined as follows: If the ol element has a start attribute, then: Let parsed be the result of parsing the value of the attribute as an integer.If parsed is not an error, then return parsed. If the ol element has a reversed attribute, then return the number of owned li elements.Return 1. The type attribute can be used to specify the kind of marker to use in the list, in the cases where that matters (e.g. because items are to be referenced by their number/letter). The attribute, if specified, must have a value that is identical to one of the characters given in the first cell of one of the rows of the following table. The type attribute represents the state given in the cell in the second column of the row whose first cell matches the attribute's value; if none of the cells match, or if the attribute is omitted, then the attribute represents the decimal state. Keyword State Description Examples for values 1-3 and 3999-4001 1 (U+0031) decimal Decimal numbers 1. 2. 3. ... 3999. 4000. 4001. ... a (U+0061) lower-alpha Lowercase latin alphabet a. b. c. ... ewu. ewv. eww. ... A (U+0041) upper-alpha Uppercase latin alphabet A. B. C. ... EWU. EWV. EWW. ... i (U+0069) lower-roman Lowercase roman numerals i. ii. iii. ... mmmcmxcix. i̅v̅. i̅v̅i. ... I (U+0049) upper-roman Uppercase roman numerals I. II. III. ... MMMCMXCIX. I̅V̅. I̅V̅I. ... User agents should render the items of the list in a manner consistent with the state of the type attribute of the ol element. Numbers less than or equal to zero should always use the decimal system regardless of the type attribute. The reversed and type IDL attributes must reflect the respective content attributes of the same name. The start IDL attribute must reflect the content attribute of the same name, with a default value of 1.

The optgroup element represents a group of option elements with a common label. The element's group of option elements consists of the option elements that are children of the optgroup element. When showing option elements in select elements, user agents should show the option elements of such groups as being related to each other and separate from other option elements. The disabled attribute is a boolean attribute and can be used to disable a group of option elements together. The label attribute must be specified. Its value gives the name of the group, for the purposes of the user interface. User agents should use this attribute's value when labeling the group of option elements in a select element. The disabled and label attributes must reflect the respective content attributes of the same name.

The option element represents an option in a select element or as part of a list of suggestions in a datalist element. In certain circumstances described in the definition of the select element, an option element can be a select element's placeholder label option. A placeholder label option does not represent an actual option, but instead represents a label for the select control. The disabled attribute is a boolean attribute. An option element is disabled if its disabled attribute is present or if it is a child of an optgroup element whose disabled attribute is present. An option element that is disabled must prevent any click events that are queued on the user interaction task source from being dispatched on the element. The label attribute provides a label for element. The label of an option element is the value of the label content attribute, if there is one and its value is not the empty string, or, otherwise, the value of the element's text IDL attribute. The label content attribute, if specified, must not be empty. The value attribute provides a value for element. The value of an option element is the value of the value content attribute, if there is one, or, if there is not, the value of the element's text IDL attribute. The selected attribute is a boolean attribute. It represents the default selectedness of the element. The dirtiness of an option element is a boolean state, initially false. It controls whether adding or removing the selected content attribute has any effect. The selectedness of an option element is a boolean state, initially false. Except where otherwise specified, when the element is created, its selectedness must be set to true if the element has a selected attribute. Whenever an option element's selected attribute is added, if its dirtiness is false, its selectedness must be set to true. Whenever an option element's selected attribute is removed, if its dirtiness is false, its selectedness must be set to false. A select element whose multiple attribute is not specified must not have more than one descendant option element with its selected attribute set. An option element's index is the number of option elements that are in the same list of options but that come before it in tree order. If the option element is not in a list of options, then the option element's index is zero. The disabled IDL attribute must reflect the content attribute of the same name. The defaultSelected IDL attribute must reflect the selected content attribute. The label IDL attribute, on getting, if there is a label content attribute, must return that attribute's value; otherwise, it must return the element's label. On setting, the element's label content attribute must be set to the new value. The value IDL attribute, on getting, must return the element's value. On setting, the element's value content attribute must be set to the new value. The selected IDL attribute, on getting, must return true if the element's selectedness is true, and false otherwise. On setting, it must set the element's selectedness to the new value, set its dirtiness to true, and then cause the element to ask for a reset. The index IDL attribute must return the element's index. The text IDL attribute, on getting, must return the result of stripping and collapsing ASCII whitespace from the concatenation of data of all the Text node descendants of the option element, in tree order, excluding any that are descendants of descendants of the option element that are themselves script or SVG script elements. The text attribute's setter must string replace all with the given value within this element. The form IDL attribute's behavior depends on whether the option element is in a select element or not. If the option has a select element as its parent, or has an optgroup element as its parent and that optgroup element has a select element as its parent, then the form IDL attribute must return the same value as the form IDL attribute on that select element. Otherwise, it must return null. A legacy factory function is provided for creating HTMLOptionElement objects (in addition to the factory methods from DOM such as createElement()): Option(text, value, defaultSelected, selected). When invoked, the legacy factory function must perform the following steps: Let document be the current global object's associated Document.Let option be the result of creating an element given document, option, and the HTML namespace.If text is not the empty string, then append to option a new Text node whose data is text.If value is given, then set an attribute value for option using "value" and value.If defaultSelected is true, then set an attribute value for option using "selected" and the empty string.If selected is true, then set option's selectedness to true; otherwise set its selectedness to false (even if defaultSelected is true).Return option.

The output element represents the result of a calculation performed by the application, or the result of a user action. The for content attribute allows an explicit relationship to be made between the result of a calculation and the elements that represent the values that went into the calculation or that otherwise influenced the calculation. The for attribute, if specified, must contain a string consisting of an unordered set of unique space-separated tokens, none of which are identical to another token and each of which must have the value of an ID of an element in the same tree. The form attribute is used to explicitly associate the output element with its form owner. The name attribute represents the element's name. The output element is associated with a form so that it can be easily referenced from the event handlers of form controls; the element's value itself is not submitted when the form is submitted. The element has a default value override (null or a string). Initially it must be null. The element's default value is determined by the following steps: If this element's default value override is non-null, then return it.Return this element's descendant text content. The reset algorithm for output elements is to run these steps: String replace all with this element's default value within this element.Set this element's default value override to null. The value getter steps are to return this's descendant text content. The value setter steps are: Set this's default value override to its default value.String replace all with the given value within this. The defaultValue getter steps are to return the result of running this's default value. The defaultValue setter steps are: If this's default value override is null, then string replace all with the given value within this and return.Set this's default value override to the given value. The type getter steps are to return "output". The htmlFor IDL attribute must reflect the for content attribute. The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The form and name IDL attributes are part of the element's forms API.

The p element represents a paragraph. The p element should not be used when a more specific element is more appropriate. List elements (in particular, ol and ul elements) cannot be children of p elements. When a sentence contains a bulleted list, therefore, one might wonder how it should be marked up. The solution is to realize that a paragraph, in HTML terms, is not a logical concept, but a structural one. In the fantastic example above, there are actually five paragraphs as defined by this specification: one before the list, one for each bullet, and one after the list. Authors wishing to conveniently style such "logical" paragraphs consisting of multiple "structural" paragraphs can use the div element instead of the p element.

The picture element is a container which provides multiple sources to its contained img element to allow authors to declaratively control or give hints to the user agent about which image resource to use, based on the screen pixel density, viewport size, image format, and other factors. It represents its children.

The pre element represents a block of preformatted text, in which structure is represented by typographic conventions rather than by elements. Some examples of cases where the pre element could be used: Including an email, with paragraphs indicated by blank lines, lists indicated by lines prefixed with a bullet, and so on.Including fragments of computer code, with structure indicated according to the conventions of that language.Displaying ASCII art. To represent a block of computer code, the pre element can be used with a code element; to represent a block of computer output the pre element can be used with a samp element. Similarly, the kbd element can be used within a pre element to indicate text that the user is to enter.

The progress element represents the completion progress of a task. The progress is either indeterminate, indicating that progress is being made but that it is not clear how much more work remains to be done before the task is complete (e.g. because the task is waiting for a remote host to respond), or the progress is a number in the range zero to a maximum, giving the fraction of work that has so far been completed. There are two attributes that determine the current task completion represented by the element. The value attribute specifies how much of the task has been completed, and the max attribute specifies how much work the task requires in total. The units are arbitrary and not specified. Authors are encouraged to also include the current value and the maximum value inline as text inside the element, so that the progress is made available to users of legacy user agents. The value and max attributes, when present, must have values that are valid floating-point numbers. The value attribute, if present, must have a value equal to or greater than zero, and less than or equal to the value of the max attribute, if present, or 1.0, otherwise. The max attribute, if present, must have a value greater than zero. User agent requirements: If the value attribute is omitted, then the progress bar is an indeterminate progress bar. Otherwise, it is a determinate progress bar. If the progress bar is a determinate progress bar and the element has a max attribute, the user agent must parse the max attribute's value according to the rules for parsing floating-point number values. If this does not result in an error, and if the parsed value is greater than zero, then the maximum value of the progress bar is that value. Otherwise, if the element has no max attribute, or if it has one but parsing it resulted in an error, or if the parsed value was less than or equal to zero, then the maximum value of the progress bar is 1.0. If the progress bar is a determinate progress bar, user agents must parse the value attribute's value according to the rules for parsing floating-point number values. If this does not result in an error and the parsed value is greater than zero, then the value of the progress bar is that parsed value. Otherwise, if parsing the value attribute's value resulted in an error or a number less than or equal to zero, then the value of the progress bar is zero. If the progress bar is a determinate progress bar, then the current value is the maximum value, if value is greater than the maximum value, and value otherwise. UA requirements for showing the progress bar: When representing a progress element to the user, the UA should indicate whether it is a determinate or indeterminate progress bar, and in the former case, should indicate the relative position of the current value relative to the maximum value. If the progress bar is an indeterminate progress bar, then the position IDL attribute must return −1. Otherwise, it must return the result of dividing the current value by the maximum value. If the progress bar is an indeterminate progress bar, then the value IDL attribute, on getting, must return 0. Otherwise, it must return the current value. On setting, the given value must be converted to the best representation of the number as a floating-point number and then the value content attribute must be set to that string. The max IDL attribute must reflect the content attribute of the same name, limited to numbers greater than zero. The default value for max is 1.0. The labels IDL attribute provides a list of the element's labels.

The q element represents some phrasing content quoted from another source. Quotation punctuation (such as quotation marks) that is quoting the contents of the element must not appear immediately before, after, or inside q elements; they will be inserted into the rendering by the user agent. Content inside a q element must be quoted from another source, whose address, if it has one, may be cited in the cite attribute. The source may be fictional, as when quoting characters in a novel or screenplay. If the cite attribute is present, it must be a valid URL potentially surrounded by spaces. To obtain the corresponding citation link, the value of the attribute must be parsed relative to the element's node document. User agents may allow users to follow such citation links, but they are primarily intended for private use (e.g., by server-side scripts collecting statistics about a site's use of quotations), not for readers. The q element must not be used in place of quotation marks that do not represent quotes; for example, it is inappropriate to use the q element for marking up sarcastic statements. The use of q elements to mark up quotations is entirely optional; using explicit quotation punctuation without q elements is just as correct.

The rp element can be used to provide parentheses or other content around a ruby text component of a ruby annotation, to be shown by user agents that don't support ruby annotations. An rp element that is a child of a ruby element represents nothing. An rp element whose parent element is not a ruby element represents its children.

The rt element marks the ruby text component of a ruby annotation. When it is the child of a ruby element, it doesn't represent anything itself, but the ruby element uses it as part of determining what it represents. An rt element that is not a child of a ruby element represents the same thing as its children.

The ruby element allows one or more spans of phrasing content to be marked with ruby annotations. Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations. In Japanese, this form of typography is also known as furigana. The content model of ruby elements consists of one or more of the following sequences: One or the other of the following: Phrasing content, but with no ruby elements and with no ruby element descendants A single ruby element that itself has no ruby element descendants One or the other of the following: One or more rt elements An rp element followed by one or more rt elements, each of which is itself followed by an rp element The ruby and rt elements can be used for a variety of kinds of annotations, including in particular (though by no means limited to) those described below. For more details on Japanese Ruby in particular, and how to render Ruby for Japanese, see Requirements for Japanese Text Layout. [JLREQ] Mono-ruby for individual base characters in Japanese One or more hiragana or katakana characters (the ruby annotation) are placed with each ideographic character (the base text). This is used to provide readings of kanji characters. Mono-ruby for compound words (jukugo) This is similar to the previous case: each ideographic character in the compound word (the base text) has its reading given in hiragana or katakana characters (the ruby annotation). The difference is that the base text segments form a compound word rather than being separate from each other. Jukugo-ruby This is semantically identical to the previous case (each individual ideographic character in the base compound word has its reading given in an annotation in hiragana or katakana characters), but the rendering is the more complicated Jukugo Ruby rendering. Group ruby for describing meanings The annotation describes the meaning of the base text, rather than (or in addition to) the pronunciation. As such, both the base text and the annotation can be multiple characters long. Group ruby for Jukuji readings A phonetic reading that corresponds to multiple base characters, because a one-to-one mapping would be difficult. (In English, the words "Colonel" and "Lieutenant" are examples of words where a direct mapping of pronunciation to individual letters is, in some dialects, rather unclear.) Text with both phonetic and semantic annotations (double-sided ruby) Sometimes, ruby styles described above are combined. If this results in two annotations covering the same single base segment, then the annotations can just be placed back to back. In more complicated situations such as the following examples, a nested ruby element is used to give the inner annotations, and then that whole ruby is then given an annotation at the "outer" level. Within a ruby element that does not have a ruby element ancestor, content is segmented and segments are placed into three categories: base text segments, annotation segments, and ignored segments. Ignored segments do not form part of the document's semantics (they consist of some inter-element whitespace and rp elements, the latter of which are used for legacy user agents that do not support ruby at all). Base text segments can overlap (with a limit of two segments overlapping any one position in the DOM, and with any segment having an earlier start point than an overlapping segment also having an equal or later end point, and any segment have a later end point than an overlapping segment also having an equal or earlier start point). Annotation segments correspond to rt elements. Each annotation segment can be associated with a base text segment, and each base text segment can have annotation segments associated with it. (In a conforming document, each base text segment is associated with at least one annotation segment, and each annotation segment is associated with one base text segment.) A ruby element represents the union of the segments of base text it contains, along with the mapping from those base text segments to annotation segments. Segments are described in terms of DOM ranges; annotation segment ranges always consist of exactly one element. [DOM] At any particular time, the segmentation and categorization of content of a ruby element is the result that would be obtained from running the following algorithm: Let base text segments be an empty list of base text segments, each potentially with a list of base text subsegments.Let annotation segments be an empty list of annotation segments, each potentially being associated with a base text segment or subsegment.Let root be the ruby element for which the algorithm is being run.If root has a ruby element ancestor, then jump to the step labeled end.Let current parent be root.Let index be 0.Let start index be null.Let parent start index be null.Let current base text be null.Start mode: If index is equal to or greater than the number of child nodes in current parent, then jump to the step labeled end mode. If the indexth node in current parent is an rt or rp element, jump to the step labeled annotation mode.Set start index to the value of index.Base mode: If the indexth node in current parent is a ruby element, and if current parent is the same element as root, then push a ruby level and then jump to the step labeled start mode.If the indexth node in current parent is an rt or rp element, then set the current base text and then jump to the step labeled annotation mode.Increment index by one.Base mode post-increment: If index is equal to or greater than the number of child nodes in current parent, then jump to the step labeled end mode.Jump back to the step labeled base mode.Annotation mode: If the indexth node in current parent is an rt element, then push a ruby annotation and jump to the step labeled annotation mode increment.If the indexth node in current parent is an rp element, jump to the step labeled annotation mode increment.If the indexth node in current parent is not a Text node, or is a Text node that is not inter-element whitespace, then jump to the step labeled base mode.Annotation mode increment: Let lookahead index be index plus one.Annotation mode white-space skipper: If lookahead index is equal to the number of child nodes in current parent then jump to the step labeled end mode.If the lookahead indexth node in current parent is an rt element or an rp element, then set index to lookahead index and jump to the step labeled annotation mode.If the lookahead indexth node in current parent is not a Text node, or is a Text node that is not inter-element whitespace, then jump to the step labeled base mode (without further incrementing index, so the inter-element whitespace seen so far becomes part of the next base text segment).Increment lookahead index by one.Jump to the step labeled annotation mode white-space skipper.End mode: If current parent is not the same element as root, then pop a ruby level and jump to the step labeled base mode post-increment.End: Return base text segments and annotation segments. Any content of the ruby element not described by segments in either of those lists is implicitly in an ignored segment. When the steps above say to set the current base text, it means to run the following steps at that point in the algorithm: Let text range be a DOM range whose start is the boundary point (current parent, start index) and whose end is the boundary point (current parent, index).Let new text segment be a base text segment described by the range annotation range. Add new text segment to base text segments.Let current base text be new text segment.Let start index be null. When the steps above say to push a ruby level, it means to run the following steps at that point in the algorithm: Let current parent be the indexth node in current parent.Let index be 0.Set saved start index to the value of start index.Let start index be null. When the steps above say to pop a ruby level, it means to run the following steps at that point in the algorithm: Let index be the position of current parent in root.Let current parent be root.Increment index by one.Set start index to the value of saved start index.Let saved start index be null. When the steps above say to push a ruby annotation, it means to run the following steps at that point in the algorithm: Let rt be the rt element that is the indexth node of current parent.Let annotation range be a DOM range whose start is the boundary point (current parent, index) and whose end is the boundary point (current parent, index plus one) (i.e. that contains only rt).Let new annotation segment be an annotation segment described by the range annotation range.If current base text is not null, associate new annotation segment with current base text.Add new annotation segment to annotation segments.

The s element represents contents that are no longer accurate or no longer relevant.

The samp element represents sample or quoted output from another program or computing system.

The script element allows authors to include dynamic script and data blocks in their documents. The element does not represent content for the user. The type attribute allows customization of the type of script represented: Omitting the attribute, setting it to the empty string, or setting it to a JavaScript MIME type essence match, means that the script is a classic script, to be interpreted according to the JavaScript Script top-level production. Classic scripts are affected by the async and defer attributes, but only when the src attribute is set. Authors should omit the type attribute instead of redundantly setting it.Setting the attribute to an ASCII case-insensitive match for the string "module" means that the script is a JavaScript module script, to be interpreted according to the JavaScript Module top-level production. Module scripts are not affected by the defer attribute, but are affected by the async attribute (regardless of the state of the src attribute).Setting the attribute to any other value means that the script is a data block, which is not processed. None of the script attributes (except type itself) have any effect on data blocks. Authors must use a valid MIME type string that is not a JavaScript MIME type essence match to denote data blocks. Classic scripts and JavaScript module scripts can be embedded inline, or be imported from an external file using the src attribute, which if specified gives the URL of the external script resource to use. If src is specified, it must be a valid non-empty URL potentially surrounded by spaces. The contents of inline script elements, or the external script resource, must conform with the requirements of the JavaScript specification's Script or Module productions, for classic scripts and JavaScript module scripts respectively. [JAVASCRIPT] The contents of the external script resource for CSS module scripts must conform to the requirements of the CSS specification. [CSS] The contents of the external script resource for JSON module scripts must conform to the requirements of the JSON specification [JSON]. When used to include data blocks, the data must be embedded inline, the format of the data must be given using the type attribute, and the contents of the script element must conform to the requirements defined for the format used. The src, async, nomodule, defer, crossorigin, integrity, and referrerpolicy attributes must not be specified. The nomodule attribute is a boolean attribute that prevents a script from being executed in user agents that support module scripts. This allows selective execution of module scripts in modern user agents and classic scripts in older user agents, as shown below. The nomodule attribute must not be specified on module scripts (and will be ignored if it is). The async and defer attributes are boolean attributes that indicate how the script should be evaluated. Classic scripts may specify defer or async, but must not specify either unless the src attribute is present. Module scripts may specify the async attribute, but must not specify the defer attribute. There are several possible modes that can be selected using these attributes, and depending on the script's type. For classic scripts, if the async attribute is present, then the classic script will be fetched in parallel to parsing and evaluated as soon as it is available (potentially before parsing completes). If the async attribute is not present but the defer attribute is present, then the classic script will be fetched in parallel and evaluated when the page has finished parsing. If neither attribute is present, then the script is fetched and evaluated immediately, blocking parsing until these are both complete. For module scripts, if the async attribute is present, then the module script and all its dependencies will be fetched in parallel to parsing, and the module script will be evaluated as soon as it is available (potentially before parsing completes). Otherwise, the module script and its dependencies will be fetched in parallel to parsing and evaluated when the page has finished parsing. (The defer attribute has no effect on module scripts.) This is all summarized in the following schematic diagram: The defer attribute may be specified even if the async attribute is specified, to cause legacy web browsers that only support defer (and not async) to fall back to the defer behavior instead of the blocking behavior that is the default. The crossorigin attribute is a CORS settings attribute. For classic scripts, it controls whether error information will be exposed, when the script is obtained from other origins. For module scripts, it controls the credentials mode used for cross-origin requests. The integrity attribute represents the integrity metadata for requests which this element is responsible for. The value is text. The integrity attribute must not be specified when the src attribute is not specified. [SRI] The referrerpolicy attribute is a referrer policy attribute. Its purpose is to set the referrer policy used when fetching the script, as well as any scripts imported from it. [REFERRERPOLICY] The blocking attribute is a blocking attribute. Changing the src, type, nomodule, async, defer, crossorigin, integrity, and referrerpolicy attributes dynamically has no direct effect; these attributes are only used at specific times described below. The IDL attributes src, type, defer, integrity, and blocking, must each reflect the respective content attributes of the same name. The referrerPolicy IDL attribute must reflect the referrerpolicy content attribute, limited to only known values. The crossOrigin IDL attribute must reflect the crossorigin content attribute, limited to only known values. The noModule IDL attribute must reflect the nomodule content attribute. The async getter steps are: If this's force async is true, then return true.If this's async content attribute is present, then return true.Return false. The async setter steps are: Set this's force async to false.If the given value is true, then set this's async content attribute to the empty string.Otherwise, remove this's async content attribute. The text attribute's getter must return this script element's child text content. The text attribute's setter must string replace all with the given value within this script element. The supports(type) method steps are: If type is "classic", then return true.If type is "module", then return true.Return false.

The section element represents a generic section of a document or application. A section, in this context, is a thematic grouping of content, typically with a heading. Examples of sections would be chapters, the various tabbed pages in a tabbed dialog box, or the numbered sections of a thesis. A web site's home page could be split into sections for an introduction, news items, and contact information.

The select element represents a control for selecting amongst a set of options. The multiple attribute is a boolean attribute. If the attribute is present, then the select element represents a control for selecting zero or more options from the list of options. If the attribute is absent, then the select element represents a control for selecting a single option from the list of options. The size attribute gives the number of options to show to the user. The size attribute, if specified, must have a value that is a valid non-negative integer greater than zero. The display size of a select element is the result of applying the rules for parsing non-negative integers to the value of element's size attribute, if it has one and parsing it is successful. If applying those rules to the attribute's value is not successful, or if the size attribute is absent, then the element's display size is 4 if the element's multiple content attribute is present, and 1 otherwise. The list of options for a select element consists of all the option element children of the select element, and all the option element children of all the optgroup element children of the select element, in tree order. The required attribute is a boolean attribute. When specified, the user will be required to select a value before submitting the form. If a select element has a required attribute specified, does not have a multiple attribute specified, and has a display size of 1; and if the value of the first option element in the select element's list of options (if any) is the empty string, and that option element's parent node is the select element (and not an optgroup element), then that option is the select element's placeholder label option. If a select element has a required attribute specified, does not have a multiple attribute specified, and has a display size of 1, then the select element must have a placeholder label option. Constraint validation: If the element has its required attribute specified, and either none of the option elements in the select element's list of options have their selectedness set to true, or the only option element in the select element's list of options with its selectedness set to true is the placeholder label option, then the element is suffering from being missing. If the multiple attribute is absent, and the element is not disabled, then the user agent should allow the user to pick an option element in its list of options that is itself not disabled. Upon this option element being picked (either through a click, or through unfocusing the element after changing its value, or through a menu command, or through any other mechanism), and before the relevant user interaction event is queued (e.g. before the click event), the user agent must set the selectedness of the picked option element to true, set its dirtiness to true, and then send select update notifications. If the multiple attribute is absent, whenever an option element in the select element's list of options has its selectedness set to true, and whenever an option element with its selectedness set to true is added to the select element's list of options, the user agent must set the selectedness of all the other option elements in its list of options to false. If the multiple attribute is absent and the element's display size is greater than 1, then the user agent should also allow the user to request that the option whose selectedness is true, if any, be unselected. Upon this request being conveyed to the user agent, and before the relevant user interaction event is queued (e.g. before the click event), the user agent must set the selectedness of that option element to false, set its dirtiness to true, and then send select update notifications. The selectedness setting algorithm, given a select element element, is to run the following steps: If element's multiple attribute is absent, and element's display size is 1, and no option elements in the element's list of options have their selectedness set to true, then set the selectedness of the first option element in the list of options in tree order that is not disabled, if any, to true, and return.If element's multiple attribute is absent, and two or more option elements in element's list of options have their selectedness set to true, then set the selectedness of all but the last option element with its selectedness set to true in the list of options in tree order to false. The option HTML element insertion steps, given insertedNode, are: If insertedNode's parent is a select element, or insertedNode's parent is an optgroup element whose parent is a select element, then run that select element's selectedness setting algorithm. The option HTML element removing steps, given removedNode and oldParent, are: If oldParent is a select element, or oldParent is an optgroup element whose parent is a select element, then run that select element's selectedness setting algorithm. If an option element in the list of options asks for a reset, then run that select element's selectedness setting algorithm. If the multiple attribute is present, and the element is not disabled, then the user agent should allow the user to toggle the selectedness of the option elements in its list of options that are themselves not disabled. Upon such an element being toggled (either through a click, or through a menu command, or any other mechanism), and before the relevant user interaction event is queued (e.g. before a related click event), the selectedness of the option element must be changed (from true to false or false to true), the dirtiness of the element must be set to true, and the user agent must send select update notifications. When the user agent is to send select update notifications, queue an element task on the user interaction task source given the select element to run these steps: Fire an event named input at the select element, with the bubbles and composed attributes initialized to true.Fire an event named change at the select element, with the bubbles attribute initialized to true. The reset algorithm for select elements is to go through all the option elements in the element's list of options, set their selectedness to true if the option element has a selected attribute, and false otherwise, set their dirtiness to false, and then have the option elements ask for a reset. The form attribute is used to explicitly associate the select element with its form owner. The name attribute represents the element's name. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The autocomplete attribute controls how the user agent provides autofill behavior. A select element that is not disabled is mutable. The type IDL attribute, on getting, must return the string "select-one" if the multiple attribute is absent, and the string "select-multiple" if the multiple attribute is present. The options IDL attribute must return an HTMLOptionsCollection rooted at the select node, whose filter matches the elements in the list of options. The options collection is also mirrored on the HTMLSelectElement object. The supported property indices at any instant are the indices supported by the object returned by the options attribute at that instant. The length IDL attribute must return the number of nodes represented by the options collection. On setting, it must act like the attribute of the same name on the options collection. The item(index) method must return the value returned by the method of the same name on the options collection, when invoked with the same argument. The namedItem(name) method must return the value returned by the method of the same name on the options collection, when invoked with the same argument. When the user agent is to set the value of a new indexed property or set the value of an existing indexed property for a select element, it must instead run the corresponding algorithm on the select element's options collection. Similarly, the add(element, before) method must act like its namesake method on that same options collection. The remove() method must act like its namesake method on that same options collection when it has arguments, and like its namesake method on the ChildNode interface implemented by the HTMLSelectElement ancestor interface Element when it has no arguments. The selectedOptions IDL attribute must return an HTMLCollection rooted at the select node, whose filter matches the elements in the list of options that have their selectedness set to true. The selectedIndex IDL attribute, on getting, must return the index of the first option element in the list of options in tree order that has its selectedness set to true, if any. If there isn't one, then it must return −1. On setting, the selectedIndex attribute must set the selectedness of all the option elements in the list of options to false, and then the option element in the list of options whose index is the given new value, if any, must have its selectedness set to true and its dirtiness set to true. The value IDL attribute, on getting, must return the value of the first option element in the list of options in tree order that has its selectedness set to true, if any. If there isn't one, then it must return the empty string. On setting, the value attribute must set the selectedness of all the option elements in the list of options to false, and then the first option element in the list of options, in tree order, whose value is equal to the given new value, if any, must have its selectedness set to true and its dirtiness set to true. The multiple, required, and size IDL attributes must reflect the respective content attributes of the same name. The size IDL attribute has a default value of zero. The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The disabled, form, and name IDL attributes are part of the element's forms API.

The slot element defines a slot. It is typically used in a shadow tree. A slot element represents its assigned nodes, if any, and its contents otherwise. The name content attribute may contain any string value. It represents a slot's name. The name IDL attribute must reflect the content attribute of the same name. The slot element has manually assigned nodes, which is an ordered set of slottables set by assign(). This set is initially empty. The assignedNodes(options) method steps are: If options["flatten"] is false, then return this's assigned nodes.Return the result of finding flattened slottables with this. The assignedElements(options) method steps are: If options["flatten"] is false, then return this's assigned nodes, filtered to contain only Element nodes.Return the result of finding flattened slottables with this, filtered to contain only Element nodes. The assign(...nodes) method steps are: For each node of this's manually assigned nodes, set node's manual slot assignment to null.Let nodesSet be a new ordered set. For each node of nodes: If node's manual slot assignment refers to a slot, then remove node from that slot's manually assigned nodes.Set node's manual slot assignment to this.Append node to nodesSet. Set this's manually assigned nodes to nodesSet.Run assign slottables for a tree for this's root.

The small element represents side comments such as small print. The small element should not be used for extended spans of text, such as multiple paragraphs, lists, or sections of text. It is only intended for short runs of text. The text of a page listing terms of use, for instance, would not be a suitable candidate for the small element: in such a case, the text is not a side comment, it is the main content of the page. The small element must not be used for subheadings; for that purpose, use the hgroup element.

The source element allows authors to specify multiple alternative source sets for img elements or multiple alternative media resources for media elements. It does not represent anything on its own. The type attribute may be present. If present, the value must be a valid MIME type string. The remainder of the requirements depend on whether the parent is a picture element or a media element: The source element's parent is a picture element The srcset attribute must be present, and is a srcset attribute. The srcset attribute contributes the image sources to the source set, if the source element is selected. If the srcset attribute has any image candidate strings using a width descriptor, the sizes attribute must also be present, and is a sizes attribute. The sizes attribute contributes the source size to the source set, if the source element is selected. The media attribute may also be present. If present, the value must contain a valid media query list. The user agent will skip to the next source element if the value does not match the environment. The source element supports dimension attributes. The img element can use the width and height attributes of a source element, instead of those on the img element itself, to determine its rendered dimensions and aspect-ratio, as defined in the Rendering section. The type attribute gives the type of the images in the source set, to allow the user agent to skip to the next source element if it does not support the given type. When a source element has a following sibling source element or img element with a srcset attribute specified, it must have at least one of the following: A media attribute specified with a value that, after stripping leading and trailing ASCII whitespace, is not the empty string and is not an ASCII case-insensitive match for the string "all".A type attribute specified. The src attribute must not be present. The source element's parent is a media element The src attribute gives the URL of the media resource. The value must be a valid non-empty URL potentially surrounded by spaces. This attribute must be present. The type attribute gives the type of the media resource, to help the user agent determine if it can play this media resource before fetching it. The codecs parameter, which certain MIME types define, might be necessary to specify exactly how the resource is encoded. [RFC6381] The srcset, sizes, and media attributes must not be present. The source HTML element insertion steps, given insertedNode, are: If insertedNode's parent is a media element that has no src attribute and whose networkState has the value NETWORK_EMPTY, then invoke that media element's resource selection algorithm.If insertedNode's next sibling is an img element and its parent is a picture element, then, count this as a relevant mutation for the img element. The source HTML element removing steps, given removedNode and oldParent, are: If removedNode's next sibling was an img element and oldParent is a picture element, then, count this as a relevant mutation for the img element. The IDL attributes src, type, srcset, sizes and media must reflect the respective content attributes of the same name.

The span element doesn't mean anything on its own, but can be useful when used together with the global attributes, e.g. class, lang, or dir. It represents its children.

The strong element represents strong importance, seriousness, or urgency for its contents. Importance: the strong element can be used in a heading, caption, or paragraph to distinguish the part that really matters from other parts that might be more detailed, more jovial, or merely boilerplate. (This is distinct from marking up subheadings, for which the hgroup element is appropriate.) For example, the first word of the previous paragraph is marked up with strong to distinguish it from the more detailed text in the rest of the paragraph. Seriousness: the strong element can be used to mark up a warning or caution notice. Urgency: the strong element can be used to denote contents that the user needs to see sooner than other parts of the document. The relative level of importance of a piece of content is given by its number of ancestor strong elements; each strong element increases the importance of its contents. Changing the importance of a piece of text with the strong element does not change the meaning of the sentence.

The style element allows authors to embed CSS style sheets in their documents. The style element is one of several inputs to the styling processing model. The element does not represent content for the user. The disabled getter steps are: If this does not have an associated CSS style sheet, return false.If this's associated CSS style sheet's disabled flag is set, return true.Return false. The disabled setter steps are: If this does not have an associated CSS style sheet, return.If the given value is true, set this's associated CSS style sheet's disabled flag. Otherwise, unset this's associated CSS style sheet's disabled flag. The media attribute says which media the styles apply to. The value must be a valid media query list. The user agent must apply the styles when the media attribute's value matches the environment and the other relevant conditions apply, and must not apply them otherwise. The default, if the media attribute is omitted, is "all", meaning that by default styles apply to all media. The blocking attribute is a blocking attribute. The title attribute on style elements defines CSS style sheet sets. If the style element has no title attribute, then it has no title; the title attribute of ancestors does not apply to the style element. If the style element is not in a document tree, then the title attribute is ignored. [CSSOM] The child text content of a style element must be that of a conformant style sheet. A style element is implicitly potentially render-blocking if the element was created by its node document's parser. The user agent must run the update a style block algorithm whenever one of the following conditions occur: The element is popped off the stack of open elements of an HTML parser or XML parser.The element is not on the stack of open elements of an HTML parser or XML parser, and it becomes connected or disconnected.The element's children changed steps run. The update a style block algorithm is as follows: Let element be the style element.If element has an associated CSS style sheet, remove the CSS style sheet in question.If element is not connected, then return. If element's type attribute is present and its value is neither the empty string nor an ASCII case-insensitive match for "text/css", then return. If the Should element's inline behavior be blocked by Content Security Policy? algorithm returns "Blocked" when executed upon the style element, "style", and the style element's child text content, then return. [CSP] Create a CSS style sheet with the following properties: typetext/cssowner nodeelementmedia The media attribute of element. title The title attribute of element, if element is in a document tree, or the empty string otherwise. alternate flagUnset.origin-clean flagSet.locationparent CSS style sheetowner CSS rulenulldisabled flagLeft at its default value.CSS rules Left uninitialized. This doesn't seem right. Presumably we should be using the element's child text content? Tracked as issue #2997. If element contributes a script-blocking style sheet, increment element's node document's script-blocking style sheet counter by 1.If element's media attribute's value matches the environment and element is potentially render-blocking, then block rendering on element. Once the attempts to obtain the style sheet's critical subresources, if any, are complete, or, if the style sheet has no critical subresources, once the style sheet has been parsed and processed, the user agent must run these steps: Fetching the critical subresources is not well-defined; probably issue #968 is the best resolution for that. In the meantime, any critical subresource request should have its render-blocking set to whether or not the style element is currently render-blocking. Let element be the style element associated with the style sheet in question.Let success be true. If the attempts to obtain any of the style sheet's critical subresources failed for any reason (e.g., DNS error, HTTP 404 response, a connection being prematurely closed, unsupported Content-Type), set success to false. Queue an element task on the networking task source given element and the following steps: If success is true, fire an event named load at element.Otherwise, fire an event named error at element. If element contributes a script-blocking style sheet: Assert: element's node document's script-blocking style sheet counter is greater than 0.Decrement element's node document's script-blocking style sheet counter by 1. Unblock rendering on element. The element must delay the load event of the element's node document until all the attempts to obtain the style sheet's critical subresources, if any, are complete. The media and blocking IDL attributes must each reflect the respective content attributes of the same name. The LinkStyle interface is also implemented by this element. [CSSOM]

The summary element represents a summary, caption, or legend for the rest of the contents of the summary element's parent details element, if any. A summary element is a summary for its parent details if the following algorithm returns true: If this summary element has no parent, then return false.Let parent be this summary element's parent.If parent is not a details element, then return false.If parent's first summary element child is not this summary element, then return false.Return true. The activation behavior of summary elements is to run the following steps: If this summary element is not the summary for its parent details, then return.Let parent be this summary element's parent. If the open attribute is present on parent, then remove it. Otherwise, set parent's open attribute to the empty string.

The table element represents data with more than one dimension, in the form of a table. The table element takes part in the table model. Tables have rows, columns, and cells given by their descendants. The rows and columns form a grid; a table's cells must completely cover that grid without overlap. Authors are encouraged to provide information describing how to interpret complex tables. Guidance on how to provide such information is given below. Tables must not be used as layout aids. Historically, some web authors have misused tables in HTML as a way to control their page layout. This usage is non-conforming, because tools attempting to extract tabular data from such documents would obtain very confusing results. In particular, users of accessibility tools like screen readers are likely to find it very difficult to navigate pages with tables used for layout. Tables can be complicated to understand and navigate. To help users with this, user agents should clearly delineate cells in a table from each other, unless the user agent has classified the table as a (non-conforming) layout table. User agents, especially those that do table analysis on arbitrary content, are encouraged to find heuristics to determine which tables actually contain data and which are merely being used for layout. This specification does not define a precise heuristic, but the following are suggested as possible indicators: Feature Indication The use of the role attribute with the value presentation Probably a layout table The use of the non-conforming border attribute with the non-conforming value 0 Probably a layout table The use of the non-conforming cellspacing and cellpadding attributes with the value 0 Probably a layout table The use of caption, thead, or th elements Probably a non-layout table The use of the headers and scope attributes Probably a non-layout table The use of the non-conforming border attribute with a value other than 0 Probably a non-layout table Explicit visible borders set using CSS Probably a non-layout table The use of the summary attribute Not a good indicator (both layout and non-layout tables have historically been given this attribute) If a table element has a (non-conforming) summary attribute, and the user agent has not classified the table as a layout table, the user agent may report the contents of that attribute to the user. In all of the following attribute and method definitions, when an element is to be table-created, that means to create an element given the table element's node document, the given local name, and the HTML namespace. The caption IDL attribute must return, on getting, the first caption element child of the table element, if any, or null otherwise. On setting, the first caption element child of the table element, if any, must be removed, and the new value, if not null, must be inserted as the first node of the table element. The createCaption() method must return the first caption element child of the table element, if any; otherwise a new caption element must be table-created, inserted as the first node of the table element, and then returned. The deleteCaption() method must remove the first caption element child of the table element, if any. The tHead IDL attribute must return, on getting, the first thead element child of the table element, if any, or null otherwise. On setting, if the new value is null or a thead element, the first thead element child of the table element, if any, must be removed, and the new value, if not null, must be inserted immediately before the first element in the table element that is neither a caption element nor a colgroup element, if any, or at the end of the table if there are no such elements. If the new value is neither null nor a thead element, then a "HierarchyRequestError" DOMException must be thrown instead. The createTHead() method must return the first thead element child of the table element, if any; otherwise a new thead element must be table-created and inserted immediately before the first element in the table element that is neither a caption element nor a colgroup element, if any, or at the end of the table if there are no such elements, and then that new element must be returned. The deleteTHead() method must remove the first thead element child of the table element, if any. The tFoot IDL attribute must return, on getting, the first tfoot element child of the table element, if any, or null otherwise. On setting, if the new value is null or a tfoot element, the first tfoot element child of the table element, if any, must be removed, and the new value, if not null, must be inserted at the end of the table. If the new value is neither null nor a tfoot element, then a "HierarchyRequestError" DOMException must be thrown instead. The createTFoot() method must return the first tfoot element child of the table element, if any; otherwise a new tfoot element must be table-created and inserted at the end of the table, and then that new element must be returned. The deleteTFoot() method must remove the first tfoot element child of the table element, if any. The tBodies attribute must return an HTMLCollection rooted at the table node, whose filter matches only tbody elements that are children of the table element. The createTBody() method must table-create a new tbody element, insert it immediately after the last tbody element child in the table element, if any, or at the end of the table element if the table element has no tbody element children, and then must return the new tbody element. The rows attribute must return an HTMLCollection rooted at the table node, whose filter matches only tr elements that are either children of the table element, or children of thead, tbody, or tfoot elements that are themselves children of the table element. The elements in the collection must be ordered such that those elements whose parent is a thead are included first, in tree order, followed by those elements whose parent is either a table or tbody element, again in tree order, followed finally by those elements whose parent is a tfoot element, still in tree order. The behavior of the insertRow(index) method depends on the state of the table. When it is called, the method must act as required by the first item in the following list of conditions that describes the state of the table and the index argument: If index is less than −1 or greater than the number of elements in rows collection:The method must throw an "IndexSizeError" DOMException.If the rows collection has zero elements in it, and the table has no tbody elements in it:The method must table-create a tbody element, then table-create a tr element, then append the tr element to the tbody element, then append the tbody element to the table element, and finally return the tr element.If the rows collection has zero elements in it:The method must table-create a tr element, append it to the last tbody element in the table, and return the tr element.If index is −1 or equal to the number of items in rows collection:The method must table-create a tr element, and append it to the parent of the last tr element in the rows collection. Then, the newly created tr element must be returned.Otherwise:The method must table-create a tr element, insert it immediately before the indexth tr element in the rows collection, in the same parent, and finally must return the newly created tr element. When the deleteRow(index) method is called, the user agent must run the following steps: If index is less than −1 or greater than or equal to the number of elements in the rows collection, then throw an "IndexSizeError" DOMException.If index is −1, then remove the last element in the rows collection from its parent, or do nothing if the rows collection is empty.Otherwise, remove the indexth element in the rows collection from its parent.

The tbody element represents a block of rows that consist of a body of data for the parent table element, if the tbody element has a parent and it is a table. The tbody element takes part in the table model. The rows attribute must return an HTMLCollection rooted at this element, whose filter matches only tr elements that are children of this element. The insertRow(index) method must act as follows: If index is less than −1 or greater than the number of elements in the rows collection, throw an "IndexSizeError" DOMException.Let table row be the result of creating an element given this element's node document, tr, and the HTML namespace.If index is −1 or equal to the number of items in the rows collection, then append table row to this element.Otherwise, insert table row as a child of this element, immediately before the indexth tr element in the rows collection.Return table row. The deleteRow(index) method must, when invoked, act as follows: If index is less than −1 or greater than or equal to the number of elements in the rows collection, then throw an "IndexSizeError" DOMException.If index is −1, then remove the last element in the rows collection from this element, or do nothing if the rows collection is empty.Otherwise, remove the indexth element in the rows collection from this element.

The td element represents a data cell in a table. The td element and its colspan, rowspan, and headers attributes take part in the table model. User agents, especially in non-visual environments or where displaying the table as a 2D grid is impractical, may give the user context for the cell when rendering the contents of a cell; for instance, giving its position in the table model, or listing the cell's header cells (as determined by the algorithm for assigning header cells). When a cell's header cells are being listed, user agents may use the value of abbr attributes on those header cells, if any, instead of the contents of the header cells themselves.

The template element is used to declare fragments of HTML that can be cloned and inserted in the document by script. In a rendering, the template element represents nothing. The template contents of a template element are not children of the element itself. Each template element has an associated DocumentFragment object that is its template contents. The template contents have no conformance requirements. When a template element is created, the user agent must run the following steps to establish the template contents: Let doc be the template element's node document's appropriate template contents owner document.Create a DocumentFragment object whose node document is doc and host is the template element.Set the template element's template contents to the newly created DocumentFragment object. A Document doc's appropriate template contents owner document is the Document returned by the following algorithm: If doc is not a Document created by this algorithm, then: If doc does not yet have an associated inert template document, then: Let new doc be a new Document (whose browsing context is null). This is "a Document created by this algorithm" for the purposes of the step above.If doc is an HTML document, mark new doc as an HTML document also.Let doc's associated inert template document be new doc. Set doc to doc's associated inert template document. Return doc. The adopting steps (with node and oldDocument as parameters) for template elements are the following: Let doc be node's node document's appropriate template contents owner document. Adopt node's template contents (a DocumentFragment object) into doc. The content IDL attribute must return the template element's template contents. The cloning steps for a template element node being cloned to a copy copy must run the following steps: If the clone children flag is not set in the calling clone algorithm, return.Let copied contents be the result of cloning all the children of node's template contents, with document set to copy's template contents's node document, and with the clone children flag set.Append copied contents to copy's template contents.

The textarea element represents a multiline plain text edit control for the element's raw value. The contents of the control represent the control's default value. The raw value of a textarea control must be initially the empty string. The readonly attribute is a boolean attribute used to control whether the text can be edited by the user or not. Constraint validation: If the readonly attribute is specified on a textarea element, the element is barred from constraint validation. A textarea element is mutable if it is neither disabled nor has a readonly attribute specified. When a textarea is mutable, its raw value should be editable by the user: the user agent should allow the user to edit, insert, and remove text, and to insert and remove line breaks in the form of U+000A LINE FEED (LF) characters. Any time the user causes the element's raw value to change, the user agent must queue an element task on the user interaction task source given the textarea element to fire an event named input at the textarea element, with the bubbles and composed attributes initialized to true. User agents may wait for a suitable break in the user's interaction before queuing the task; for example, a user agent could wait for the user to have not hit a key for 100ms, so as to only fire the event when the user pauses, instead of continuously for each keystroke. A textarea element's dirty value flag must be set to true whenever the user interacts with the control in a way that changes the raw value. The cloning steps for textarea elements must propagate the raw value and dirty value flag from the node being cloned to the copy. The children changed steps for textarea elements must, if the element's dirty value flag is false, set the element's raw value to its child text content. The reset algorithm for textarea elements is to set the dirty value flag back to false, and set the raw value of element to its child text content. When a textarea element is popped off the stack of open elements of an HTML parser or XML parser, then the user agent must invoke the element's reset algorithm. If the element is mutable, the user agent should allow the user to change the writing direction of the element, setting it either to a left-to-right writing direction or a right-to-left writing direction. If the user does so, the user agent must then run the following steps: Set the element's dir attribute to "ltr" if the user selected a left-to-right writing direction, and "rtl" if the user selected a right-to-left writing direction.Queue an element task on the user interaction task source given the textarea element to fire an event named input at the textarea element, with the bubbles and composed attributes initialized to true. The cols attribute specifies the expected maximum number of characters per line. If the cols attribute is specified, its value must be a valid non-negative integer greater than zero. If applying the rules for parsing non-negative integers to the attribute's value results in a number greater than zero, then the element's character width is that value; otherwise, it is 20. The user agent may use the textarea element's character width as a hint to the user as to how many characters the server prefers per line (e.g. for visual user agents by making the width of the control be that many characters). In visual renderings, the user agent should wrap the user's input in the rendering so that each line is no wider than this number of characters. The rows attribute specifies the number of lines to show. If the rows attribute is specified, its value must be a valid non-negative integer greater than zero. If applying the rules for parsing non-negative integers to the attribute's value results in a number greater than zero, then the element's character height is that value; otherwise, it is 2. Visual user agents should set the height of the control to the number of lines given by character height. The wrap attribute is an enumerated attribute with two keywords and states: the soft keyword which maps to the Soft state, and the hard keyword which maps to the Hard state. The missing value default and invalid value default are the Soft state. The Soft state indicates that the text in the textarea is not to be wrapped when it is submitted (though it can still be wrapped in the rendering). The Hard state indicates that the text in the textarea is to have newlines added by the user agent so that the text is wrapped when it is submitted. If the element's wrap attribute is in the Hard state, the cols attribute must be specified. For historical reasons, the element's value is normalized in three different ways for three different purposes. The raw value is the value as it was originally set. It is not normalized. The API value is the value used in the value IDL attribute, textLength IDL attribute, and by the maxlength and minlength content attributes. It is normalized so that line breaks use U+000A LINE FEED (LF) characters. Finally, there is the value, as used in form submission and other processing models in this specification. It is normalized as for the API value, and in addition, if necessary given the element's wrap attribute, additional line breaks are inserted to wrap the text at the given width. The algorithm for obtaining the element's API value is to return the element's raw value, with newlines normalized. The element's value is defined to be the element's API value with the textarea wrapping transformation applied. The textarea wrapping transformation is the following algorithm, as applied to a string: If the element's wrap attribute is in the Hard state, insert U+000A LINE FEED (LF) characters into the string using an implementation-defined algorithm so that each line has no more than character width characters. For the purposes of this requirement, lines are delimited by the start of the string, the end of the string, and U+000A LINE FEED (LF) characters. The maxlength attribute is a form control maxlength attribute. If the textarea element has a maximum allowed value length, then the element's children must be such that the length of the value of the element's descendant text content with newlines normalized is equal to or less than the element's maximum allowed value length. The minlength attribute is a form control minlength attribute. The required attribute is a boolean attribute. When specified, the user will be required to enter a value before submitting the form. Constraint validation: If the element has its required attribute specified, and the element is mutable, and the element's value is the empty string, then the element is suffering from being missing. The placeholder attribute represents a short hint (a word or short phrase) intended to aid the user with data entry when the control has no value. A hint could be a sample value or a brief description of the expected format. The placeholder attribute should not be used as an alternative to a label. For a longer hint or other advisory text, the title attribute is more appropriate. User agents should present this hint to the user when the element's value is the empty string and the control is not focused (e.g. by displaying it inside a blank unfocused control). All U+000D CARRIAGE RETURN U+000A LINE FEED character pairs (CRLF) in the hint, as well as all other U+000D CARRIAGE RETURN (CR) and U+000A LINE FEED (LF) characters in the hint, must be treated as line breaks when rendering the hint. If a user agent normally doesn't show this hint to the user when the control is focused, then the user agent should nonetheless show the hint for the control if it was focused as a result of the autofocus attribute, since in that case the user will not have had an opportunity to examine the control before focusing it. The name attribute represents the element's name. The dirname attribute controls how the element's directionality is submitted. The disabled attribute is used to make the control non-interactive and to prevent its value from being submitted. The form attribute is used to explicitly associate the textarea element with its form owner. The autocomplete attribute controls how the user agent provides autofill behavior. The cols, placeholder, required, rows, and wrap IDL attributes must reflect the respective content attributes of the same name. The cols and rows attributes are limited to only non-negative numbers greater than zero with fallback. The cols IDL attribute's default value is 20. The rows IDL attribute's default value is 2. The dirName IDL attribute must reflect the dirname content attribute. The maxLength IDL attribute must reflect the maxlength content attribute, limited to only non-negative numbers. The minLength IDL attribute must reflect the minlength content attribute, limited to only non-negative numbers. The readOnly IDL attribute must reflect the readonly content attribute. The type IDL attribute must return the value "textarea". The defaultValue attribute's getter must return the element's child text content. The defaultValue attribute's setter must string replace all with the given value within this element. The value IDL attribute must, on getting, return the element's API value. On setting, it must perform the following steps: Let oldAPIValue be this element's API value.Set this element's raw value to the new value.Set this element's dirty value flag to true.If the new API value is different from oldAPIValue, then move the text entry cursor position to the end of the text control, unselecting any selected text and resetting the selection direction to "none". The textLength IDL attribute must return the length of the element's API value. The willValidate, validity, and validationMessage IDL attributes, and the checkValidity(), reportValidity(), and setCustomValidity() methods, are part of the constraint validation API. The labels IDL attribute provides a list of the element's labels. The select(), selectionStart, selectionEnd, selectionDirection, setRangeText(), and setSelectionRange() methods and IDL attributes expose the element's text selection. The disabled, form, and name IDL attributes are part of the element's forms API.

The tfoot element represents the block of rows that consist of the column summaries (footers) for the parent table element, if the tfoot element has a parent and it is a table. The tfoot element takes part in the table model.

The th element represents a header cell in a table. The th element may have a scope content attribute specified. The scope attribute is an enumerated attribute with five states, four of which have explicit keywords: The row keyword, which maps to the row stateThe row state means the header cell applies to some of the subsequent cells in the same row(s).The col keyword, which maps to the column stateThe column state means the header cell applies to some of the subsequent cells in the same column(s).The rowgroup keyword, which maps to the row group stateThe row group state means the header cell applies to all the remaining cells in the row group. A th element's scope attribute must not be in the row group state if the element is not anchored in a row group.The colgroup keyword, which maps to the column group stateThe column group state means the header cell applies to all the remaining cells in the column group. A th element's scope attribute must not be in the column group state if the element is not anchored in a column group.The auto stateThe auto state makes the header cell apply to a set of cells selected based on context. The scope attribute's missing value default and invalid value default are the auto state. The th element may have an abbr content attribute specified. Its value must be an alternative label for the header cell, to be used when referencing the cell in other contexts (e.g. when describing the header cells that apply to a data cell). It is typically an abbreviated form of the full header cell, but can also be an expansion, or merely a different phrasing. The th element and its colspan, rowspan, headers, and scope attributes take part in the table model.

The thead element represents the block of rows that consist of the column labels (headers) for the parent table element, if the thead element has a parent and it is a table. The thead element takes part in the table model.

The time element represents its contents, along with a machine-readable form of those contents in the datetime attribute. The kind of content is limited to various kinds of dates, times, time-zone offsets, and durations, as described below. The datetime attribute may be present. If present, its value must be a representation of the element's contents in a machine-readable format. A time element that does not have a datetime content attribute must not have any element descendants. The datetime value of a time element is the value of the element's datetime content attribute, if it has one, otherwise the child text content of the time element. The datetime value of a time element must match one of the following syntaxes. A valid month string 2011-11 A valid date string 2011-11-18 A valid yearless date string 11-18 A valid time string 14:54 14:54:39 14:54:39.929 A valid local date and time string 2011-11-18T14:54 2011-11-18T14:54:39 2011-11-18T14:54:39.929 2011-11-18 14:54 2011-11-18 14:54:39 2011-11-18 14:54:39.929 A valid time-zone offset string Z +0000 +00:00 -0800 -08:00 A valid global date and time string 2011-11-18T14:54Z 2011-11-18T14:54:39Z 2011-11-18T14:54:39.929Z 2011-11-18T14:54+0000 2011-11-18T14:54:39+0000 2011-11-18T14:54:39.929+0000 2011-11-18T14:54+00:00 2011-11-18T14:54:39+00:00 2011-11-18T14:54:39.929+00:00 2011-11-18T06:54-0800 2011-11-18T06:54:39-0800 2011-11-18T06:54:39.929-0800 2011-11-18T06:54-08:00 2011-11-18T06:54:39-08:00 2011-11-18T06:54:39.929-08:00 2011-11-18 14:54Z 2011-11-18 14:54:39Z 2011-11-18 14:54:39.929Z 2011-11-18 14:54+0000 2011-11-18 14:54:39+0000 2011-11-18 14:54:39.929+0000 2011-11-18 14:54+00:00 2011-11-18 14:54:39+00:00 2011-11-18 14:54:39.929+00:00 2011-11-18 06:54-0800 2011-11-18 06:54:39-0800 2011-11-18 06:54:39.929-0800 2011-11-18 06:54-08:00 2011-11-18 06:54:39-08:00 2011-11-18 06:54:39.929-08:00 A valid week string 2011-W47 Four or more ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0) 2011 0001 A valid duration string PT4H18M3S 4h 18m 3s The machine-readable equivalent of the element's contents must be obtained from the element's datetime value by using the following algorithm: If parsing a month string from the element's datetime value returns a month, that is the machine-readable equivalent; return.If parsing a date string from the element's datetime value returns a date, that is the machine-readable equivalent; return.If parsing a yearless date string from the element's datetime value returns a yearless date, that is the machine-readable equivalent; return.If parsing a time string from the element's datetime value returns a time, that is the machine-readable equivalent; return.If parsing a local date and time string from the element's datetime value returns a local date and time, that is the machine-readable equivalent; return.If parsing a time-zone offset string from the element's datetime value returns a time-zone offset, that is the machine-readable equivalent; return.If parsing a global date and time string from the element's datetime value returns a global date and time, that is the machine-readable equivalent; return.If parsing a week string from the element's datetime value returns a week, that is the machine-readable equivalent; return.If the element's datetime value consists of only ASCII digits, at least one of which is not U+0030 DIGIT ZERO (0), then the machine-readable equivalent is the base-ten interpretation of those digits, representing a year; return.If parsing a duration string from the element's datetime value returns a duration, that is the machine-readable equivalent; return.There is no machine-readable equivalent. The dateTime IDL attribute must reflect the element's datetime content attribute.

The title element represents the document's title or name. Authors should use titles that identify their documents even when they are used out of context, for example in a user's history or bookmarks, or in search results. The document's title is often different from its first heading, since the first heading does not have to stand alone when taken out of context. There must be no more than one title element per document. The text attribute's getter must return this title element's child text content. The text attribute's setter must string replace all with the given value within this title element. The string to use as the document's title is given by the document.title IDL attribute. User agents should use the document's title when referring to the document in their user interface. When the contents of a title element are used in this way, the directionality of that title element should be used to set the directionality of the document's title in the user interface.

The tr element represents a row of cells in a table. The tr element takes part in the table model. The rowIndex attribute must, if this element has a parent table element, or a parent tbody, thead, or tfoot element and a grandparent table element, return the index of this tr element in that table element's rows collection. If there is no such table element, then the attribute must return −1. The sectionRowIndex attribute must, if this element has a parent table, tbody, thead, or tfoot element, return the index of the tr element in the parent element's rows collection (for tables, that's HTMLTableElement's rows collection; for table sections, that's HTMLTableSectionElement's rows collection). If there is no such parent element, then the attribute must return −1. The cells attribute must return an HTMLCollection rooted at this tr element, whose filter matches only td and th elements that are children of the tr element. The insertCell(index) method must act as follows: If index is less than −1 or greater than the number of elements in the cells collection, then throw an "IndexSizeError" DOMException.Let table cell be the result of creating an element given this tr element's node document, td, and the HTML namespace.If index is equal to −1 or equal to the number of items in cells collection, then append table cell to this tr element.Otherwise, insert table cell as a child of this tr element, immediately before the indexth td or th element in the cells collection.Return table cell. The deleteCell(index) method must act as follows: If index is less than −1 or greater than or equal to the number of elements in the cells collection, then throw an "IndexSizeError" DOMException.If index is −1, then remove the last element in the cells collection from its parent, or do nothing if the cells collection is empty.Otherwise, remove the indexth element in the cells collection from its parent.

The track element allows authors to specify explicit external timed text tracks for media elements. It does not represent anything on its own. The kind attribute is an enumerated attribute. The following table lists the keywords defined for this attribute. The keyword given in the first cell of each row maps to the state given in the second cell. Keyword State Brief description subtitles Subtitles Transcription or translation of the dialogue, suitable for when the sound is available but not understood (e.g. because the user does not understand the language of the media resource's audio track). Overlaid on the video. captions Captions Transcription or translation of the dialogue, sound effects, relevant musical cues, and other relevant audio information, suitable for when sound is unavailable or not clearly audible (e.g. because it is muted, drowned-out by ambient noise, or because the user is deaf). Overlaid on the video; labeled as appropriate for the hard-of-hearing. descriptions Descriptions Textual descriptions of the video component of the media resource, intended for audio synthesis when the visual component is obscured, unavailable, or not usable (e.g. because the user is interacting with the application without a screen while driving, or because the user is blind). Synthesized as audio. chapters Chapters metadata Tracks intended for use from script. Not displayed by the user agent. metadata Metadata The attribute may be omitted. The missing value default is the subtitles state. The invalid value default is the metadata state. The src attribute gives the URL of the text track data. The value must be a valid non-empty URL potentially surrounded by spaces. This attribute must be present. If the element has a src attribute whose value is not the empty string and whose value, when the attribute was set, could be successfully parsed relative to the element's node document, then the element's track URL is the resulting URL string. Otherwise, the element's track URL is the empty string. If the element's track URL identifies a WebVTT resource, and the element's kind attribute is not in the chapters metadata or metadata state, then the WebVTT file must be a WebVTT file using cue text. [WEBVTT] The srclang attribute gives the language of the text track data. The value must be a valid BCP 47 language tag. This attribute must be present if the element's kind attribute is in the subtitles state. [BCP47] If the element has a srclang attribute whose value is not the empty string, then the element's track language is the value of the attribute. Otherwise, the element has no track language. The label attribute gives a user-readable title for the track. This title is used by user agents when listing subtitle, caption, and audio description tracks in their user interface. The value of the label attribute, if the attribute is present, must not be the empty string. Furthermore, there must not be two track element children of the same media element whose kind attributes are in the same state, whose srclang attributes are both missing or have values that represent the same language, and whose label attributes are again both missing or both have the same value. If the element has a label attribute whose value is not the empty string, then the element's track label is the value of the attribute. Otherwise, the element's track label is an empty string. The default attribute is a boolean attribute, which, if specified, indicates that the track is to be enabled if the user's preferences do not indicate that another track would be more appropriate. Each media element must have no more than one track element child whose kind attribute is in the subtitles or captions state and whose default attribute is specified. Each media element must have no more than one track element child whose kind attribute is in the description state and whose default attribute is specified. Each media element must have no more than one track element child whose kind attribute is in the chapters metadata state and whose default attribute is specified. The readyState attribute must return the numeric value corresponding to the text track readiness state of the track element's text track, as defined by the following list: NONE (numeric value 0)The text track not loaded state.LOADING (numeric value 1)The text track loading state.LOADED (numeric value 2)The text track loaded state.ERROR (numeric value 3)The text track failed to load state. The track IDL attribute must, on getting, return the track element's text track's corresponding TextTrack object. The src, srclang, label, and default IDL attributes must reflect the respective content attributes of the same name. The kind IDL attribute must reflect the content attribute of the same name, limited to only known values.

The u element represents a span of text with an unarticulated, though explicitly rendered, non-textual annotation, such as labeling the text as being a proper name in Chinese text (a Chinese proper name mark), or labeling the text as being misspelt. In most cases, another element is likely to be more appropriate: for marking stress emphasis, the em element should be used; for marking key words or phrases either the b element or the mark element should be used, depending on the context; for marking book titles, the cite element should be used; for labeling text with explicit textual annotations, the ruby element should be used; for technical terms, taxonomic designation, transliteration, a thought, or for labeling ship names in Western texts, the i element should be used.

The ul element represents a list of items, where the order of the items is not important — that is, where changing the order would not materially change the meaning of the document. The items of the list are the li element child nodes of the ul element.

The var element represents a variable. This could be an actual variable in a mathematical expression or programming context, an identifier representing a constant, a symbol identifying a physical quantity, a function parameter, or just be a term used as a placeholder in prose. For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions.

A video element is used for playing videos or movies, and audio files with captions. Content may be provided inside the video element. User agents should not show this content to the user; it is intended for older web browsers which do not support video, so that legacy video plugins can be tried, or to show text to the users of these older browsers informing them of how to access the video contents. The video element is a media element whose media data is ostensibly video data, possibly with associated audio data. The src, crossorigin, preload, autoplay, loop, muted, and controls attributes are the attributes common to all media elements. The poster attribute gives the URL of an image file that the user agent can show while no video data is available. The attribute, if present, must contain a valid non-empty URL potentially surrounded by spaces. If the specified resource is to be used, then, when the element is created or when the poster attribute is set, changed, or removed, the user agent must run the following steps to determine the element's poster frame (regardless of the value of the element's show poster flag): If there is an existing instance of this algorithm running for this video element, abort that instance of this algorithm without changing the poster frame.If the poster attribute's value is the empty string or if the attribute is absent, then there is no poster frame; return.Parse the poster attribute's value relative to the element's node document. If this fails, then there is no poster frame; return.Let request be a new request whose URL is the resulting URL record, client is the element's node document's relevant settings object, destination is "image", credentials mode is "include", and whose use-URL-credentials flag is set. Fetch request, with processResponseEndOfBody given response res set to finalize and report timing with res, the element's node document's relevant global object, and "video". This must delay the load event of the element's node document.If an image is thus obtained, the poster frame is that image. Otherwise, there is no poster frame. The playsinline attribute is a boolean attribute. If present, it serves as a hint to the user agent that the video ought to be displayed "inline" in the document by default, constrained to the element's playback area, instead of being displayed fullscreen or in an independent resizable window. A video element represents what is given for the first matching condition in the list below: When no video data is available (the element's readyState attribute is either HAVE_NOTHING, or HAVE_METADATA but no video data has yet been obtained at all, or the element's readyState attribute is any subsequent value but the media resource does not have a video channel)The video element represents its poster frame, if any, or else transparent black with no intrinsic dimensions.When the video element is paused, the current playback position is the first frame of video, and the element's show poster flag is setThe video element represents its poster frame, if any, or else the first frame of the video.When the video element is paused, and the frame of video corresponding to the current playback position is not available (e.g. because the video is seeking or buffering)When the video element is neither potentially playing nor paused (e.g. when seeking or stalled)The video element represents the last frame of the video to have been rendered.When the video element is pausedThe video element represents the frame of video corresponding to the current playback position.Otherwise (the video element has a video channel and is potentially playing)The video element represents the frame of video at the continuously increasing "current" position. When the current playback position changes such that the last frame rendered is no longer the frame corresponding to the current playback position in the video, the new frame must be rendered. Frames of video must be obtained from the video track that was selected when the event loop last reached step 1. The video element also represents any text track cues whose text track cue active flag is set and whose text track is in the showing mode, and any audio from the media resource, at the current playback position. Any audio associated with the media resource must, if played, be played synchronized with the current playback position, at the element's effective media volume. The user agent must play the audio from audio tracks that were enabled when the event loop last reached step 1. In addition to the above, the user agent may provide messages to the user (such as "buffering", "no video loaded", "error", or more detailed information) by overlaying text or icons on the video or other areas of the element's playback area, or in another appropriate manner. User agents that cannot render the video may instead make the element represent a link to an external video playback utility or to the video data itself. When a video element's media resource has a video channel, the element provides a paint source whose width is the media resource's intrinsic width, whose height is the media resource's intrinsic height, and whose appearance is the frame of video corresponding to the current playback position, if that is available, or else (e.g. when the video is seeking or buffering) its previous appearance, if any, or else (e.g. because the video is still loading the first frame) blackness. The intrinsic width and intrinsic height of the media resource are the dimensions of the resource in CSS pixels after taking into account the resource's dimensions, aspect ratio, clean aperture, resolution, and so forth, as defined for the format used by the resource. If an anamorphic format does not define how to apply the aspect ratio to the video data's dimensions to obtain the "correct" dimensions, then the user agent must apply the ratio by increasing one dimension and leaving the other unchanged. The videoWidth IDL attribute must return the intrinsic width of the video in CSS pixels. The videoHeight IDL attribute must return the intrinsic height of the video in CSS pixels. If the element's readyState attribute is HAVE_NOTHING, then the attributes must return 0. Whenever the intrinsic width or intrinsic height of the video changes (including, for example, because the selected video track was changed), if the element's readyState attribute is not HAVE_NOTHING, the user agent must queue a media element task given the media element to fire an event named resize at the media element. The video element supports dimension attributes. In the absence of style rules to the contrary, video content should be rendered inside the element's playback area such that the video content is shown centered in the playback area at the largest possible size that fits completely within it, with the video content's aspect ratio being preserved. Thus, if the aspect ratio of the playback area does not match the aspect ratio of the video, the video will be shown letterboxed or pillarboxed. Areas of the element's playback area that do not contain the video represent nothing. The intrinsic width of a video element's playback area is the intrinsic width of the poster frame, if that is available and the element currently represents its poster frame; otherwise, it is the intrinsic width of the video resource, if that is available; otherwise the intrinsic width is missing. The intrinsic height of a video element's playback area is the intrinsic height of the poster frame, if that is available and the element currently represents its poster frame; otherwise it is the intrinsic height of the video resource, if that is available; otherwise the intrinsic height is missing. The default object size is a width of 300 CSS pixels and a height of 150 CSS pixels. [CSSIMAGES] User agents should provide controls to enable or disable the display of closed captions, audio description tracks, and other additional data associated with the video stream, though such features should, again, not interfere with the page's normal rendering. User agents may allow users to view the video content in manners more suitable to the user, such as fullscreen or in an independent resizable window. User agents may even trigger such a viewing mode by default upon playing a video, although they should not do so when the playsinline attribute is specified. As with the other user interface features, controls to enable this should not interfere with the page's normal rendering unless the user agent is exposing a user interface. In such an independent viewing mode, however, user agents may make full user interfaces visible, even if the controls attribute is absent. User agents may allow video playback to affect system features that could interfere with the user's experience; for example, user agents could disable screensavers while video playback is in progress. The poster IDL attribute must reflect the poster content attribute. The playsInline IDL attribute must reflect the playsinline content attribute.

The wbr element represents a line break opportunity. Any content inside wbr elements must not be considered part of the surrounding text. var wbr = document.createElement("wbr"); wbr.textContent = "This is wrong"; document.body.appendChild(wbr);