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Test Rule: Element with lang attribute has valid language tag

Applicability

This rule applies to any HTML element with a lang attribute value that is not empty ("") and for which all of the following is true:

Expectation

For each test target, the lang attribute value has a known primary language tag.

Assumptions

Accessibility Support

There are differences in how assistive technologies handle unknown and invalid language tags. Some will default to the language of the page, whereas others will default to the closest ancestor with a valid lang attribute.

Background

Bibliography

Accessibility Requirements Mapping

Input Aspects

The following aspects are required in using this rule.

Test Cases

Passed

Passed Example 1

This article element has a lang attribute value which has a known primary language tag.

<html>
	<body>
		<article lang="en">
			They wandered into a strange Tiki bar on the edge of the small beach town.
		</article>
	</body>
</html>

Passed Example 2

This blockquote element has a lang attribute value which has a known primary language tag. The region section (“CH”) in the value is ignored by the rule (and the definition of known primary language tag).

<html>
	<body>
		<blockquote lang="fr-CH">
			Ils ont trouvé un étrange bar Tiki aux abords de la petite ville balnéaire.
		</blockquote>
	</body>
</html>

Passed Example 3

This p element has a lang attribute value which has a known primary language tag, but a syntactically invalid region subtag which is ignored by the rule.

<html>
	<body>
		<p lang="en-US-GB">
			They wandered into a strange Tiki bar on the edge of the small beach town.
		</p>
	</body>
</html>

Passed Example 4

This div element has a valid lang attribute value. There is no text inheriting its programmatic language from the article element, therefore its lang attribute is not considered by the rule.

<html>
	<body>
		<article lang="invalid">
			<div lang="en">
				They wandered into a strange Tiki bar on the edge of the small beach town.
			</div>
		</article>
	</body>
</html>

Passed Example 5

This div element has a valid lang attribute value. The accessible name of the image is text inheriting its programmatic language from the div element.

<html>
	<body>
		<div lang="en">
			<img src="/test-assets/shared/fireworks.jpg" alt="Fireworks over Paris" />
		</div>
	</body>
</html>

Failed

Failed Example 1

This article element has a lang attribute value which does not have a known primary language tag because its primary language subtag does not exist in the language subtag registry.

<html>
	<body>
		<article lang="dutch">
			Zij liepen een vreemde Tiki bar binnen, aan de rand van een dorpje aan het strand.
		</article>
	</body>
</html>

Failed Example 2

This article element has a lang attribute value which has no known primary language tag.

<html>
	<body>
		<article lang="#!">
			They wandered into a strange Tiki bar on the edge of the small beach town.
		</article>
	</body>
</html>

Failed Example 3

This article element has a lang attribute value which consists of only whitespace and thus has no known primary language tag.

<html>
	<body>
		<article lang="  ">
			They wandered into a strange Tiki bar on the edge of the small beach town.
		</article>
	</body>
</html>

Failed Example 4

The lang attribute value does not have a valid language tag. The lang attribute must be valid because the content is visible.

<html>
	<body>
		<article lang="english">
			<p aria-hidden="true">
				They wandered into a strange Tiki bar on the edge of the small beach town.
			</p>
		</article>
	</body>
</html>

Failed Example 5

The lang attribute value does not have a valid language tag, and its descendant is not visible though it is still included in the accessibility tree.

<html>
	<body>
		<article lang="English">
			<p style="position: absolute; top: -9999px">
				They wandered into a strange Tiki bar on the edge of the small beach town.
			</p>
		</article>
	</body>
</html>

Failed Example 6

This div element has an invalid lang attribute value. There is no text inheriting its programmatic language from the article element, therefore its lang attribute is not considered by the rule.

<html>
	<body>
		<article lang="en">
			<div lang="invalid">
				They wandered into a strange Tiki bar on the edge of the small beach town.
			</div>
		</article>
	</body>
</html>

Failed Example 7

This div element has an invalid lang attribute value. The accessible name of the image is text inheriting its programmatic language from the div element.

<html>
	<body>
		<div lang="invalid">
			<img src="/test-assets/shared/fireworks.jpg" alt="Fireworks over Paris" />
		</div>
	</body>
</html>

Failed Example 8

The lang attribute value of this p element is an iso 639.2 three letters code, which has no known primary language tag.

<html lang="en">
	<body>
		<p lang="eng">I love ACT rules!</p>
	</body>
</html>

Failed Example 9

The lang attribute value of this p element is a grandfathered tag, which has no known primary language tag.

<html lang="lb">
	<body>
		<p lang="i-lux">Lëtzebuerg ass e Land an Europa.</p>
	</body>
</html>

Inapplicable

Inapplicable Example 1

There is no element with a lang attribute value which is a descendant of a body element.

<html lang="en">
	<body>
		They wandered into a strange Tiki bar on the edge of the small beach town.
	</body>
</html>

Inapplicable Example 2

There is no element which is a descendant of a body element and has a non-empty lang attribute value.

<html lang="en">
	<body>
		<article lang="">
			They wandered into a strange Tiki bar on the edge of the small beach town.
		</article>
	</body>
</html>

Inapplicable Example 3

There is no element with a text node as a descendant in the flat tree that is either visible or included in the accessibility tree.

<html lang="en">
	<body>
		<p lang="hidden">
			<span style="display: none;">
				They wandered into a strange Tiki bar on the edge of the small beach town.
			</span>
		</p>
	</body>
</html>

Inapplicable Example 4

There is no text inheriting its programmatic language from this div element.

<html>
	<body>
		<div lang="invalid">
			<img src="/test-assets/shared/fireworks.jpg" alt="" />
		</div>
	</body>
</html>

Glossary

Accessible Name

The accessible name is the programmatically determined name of a user interface element that is included in the accessibility tree.

The accessible name is calculated using the accessible name and description computation.

For native markup languages, such as HTML and SVG, additional information on how to calculate the accessible name can be found in HTML Accessibility API Mappings 1.0, Accessible Name and Description Computation (working draft) and SVG Accessibility API Mappings, Name and Description (working draft).

For more details, see examples of accessible name.

Note: As per the accessible name and description computation, each element always has an accessible name. When no accessible name is provided, the element will nonetheless be assigned an empty ("") one.

Note: As per the accessible name and description computation, accessible names are flat string trimmed of leading and trailing whitespace. Notably, it is not possible for a non-empty accessible name to be composed only of whitespace since these must be trimmed.

Attribute value

The attribute value of a content attribute set on an HTML element is the value that the attribute gets after being parsed and computed according to specifications. It may differ from the value that is actually written in the HTML code due to trimming whitespace or non-digits characters, default values, or case-insensitivity.

Some notable case of attribute value, among others:

This list is not exhaustive, and only serves as an illustration for some of the most common cases.

The attribute value of an IDL attribute is the value returned on getting it. Note that when an IDL attribute reflects a content attribute, they have the same attribute value.

Focusable

Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs are exposed to assistive technologies. This allows users of assistive technology to access the elements in a way that meets the requirements of the individual user.

The general rules for when elements are included in the accessibility tree are defined in the core accessibility API mappings. For native markup languages, such as HTML and SVG, additional rules for when elements are included in the accessibility tree can be found in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).

For more details, see examples of included in the accessibility tree.

Programmatically hidden elements are removed from the accessibility tree. However, some browsers will leave focusable elements with an aria-hidden attribute set to true in the accessibility tree. Because they are hidden, these elements are considered not included in the accessibility tree. This may cause confusion for users of assistive technologies because they may still be able to interact with these focusable elements using sequential keyboard navigation, even though the element should not be included in the accessibility tree.

Known Primary Language Tag

A language tag has a known primary language tag if its primary language subtag exists in the language subtag registry with a Type field whose field-body value is language.

A “language tag” is here to be understood as in the first paragraph of the RFC 5646 language tag syntax, i.e. a sequence of subtags separated by hyphens, where a subtag is any sequence of alphanumerical characters. Language tag that are not valid according to the stricter RFC 5646 syntax (and ABNF grammar) definition can still have a known primary language tag. User agents and assistive technologies are more lenient in what they accept. This definition is consistent with the behavior of the :lang() pseudo-selector as defined by Selectors Level 3.

As an example, de-hello would be an accepted way to indicate German in current user agents and assistive technologies, despite not being valid according to RFC 5646 grammar. It has a known primary language tag (namely, de).

As a consequence of this definition, however, grandfathered tags do not have a known primary language tag.

Subtags, notably the primary language subtag, are case insensitive. Comparison with the language subtag registry must be done in a case insensitive way.

Namespaced Element

An element with a specific namespaceURI value from HTML namespaces. For example an “SVG element” is any element with the “SVG namespace”, which is http://www.w3.org/2000/svg.

Namespaced elements are not limited to elements described in a specification. They also include custom elements. Elements such as a and title have a different namespace depending on where they are used. For example a title in an HTML page usually has the HTML namespace. When used in an svg element, a title element has the SVG namespace instead.

Outcome

An outcome is a conclusion that comes from evaluating an ACT Rule on a test subject or one of its constituent test target. An outcome can be one of the three following types:

Note: A rule has one passed or failed outcome for every test target. When there are no test targets the rule has one inapplicable outcome. This means that each test subject will have one or more outcomes.

Note: Implementations using the EARL10-Schema can express the outcome with the outcome property. In addition to passed, failed and inapplicable, EARL 1.0 also defined an incomplete outcome. While this cannot be the outcome of an ACT Rule when applied in its entirety, it often happens that rules are only partially evaluated. For example, when applicability was automated, but the expectations have to be evaluated manually. Such “interim” results can be expressed with the incomplete outcome.

Programmatically Hidden

An HTML element is programmatically hidden if either it has a computed CSS property visibility whose value is not visible; or at least one of the following is true for any of its inclusive ancestors in the flat tree:

Note: Contrarily to the other conditions, the visibility CSS property may be reverted by descendants.

Text Inheriting its Programmatic Language from an Element

The text inheriting its programmatic language from an element E is composed of all the following texts:

An element F is an element inheriting its programmatic language from an element E if at least one of the following conditions is true (recursively):

Visible

Content perceivable through sight.

Content is considered visible if making it fully transparent would result in a difference in the pixels rendered for any part of the document that is currently within the viewport or can be brought into the viewport via scrolling.

Content is defined in WCAG.

For more details, see examples of visible.

Whitespace

Whitespace are characters that have the Unicode “White_Space” property in the Unicode properties list.

This includes:

Implementations

This section is not part of the official rule. It is populated dynamically and not accounted for in the change history or the last modified date.

Implementation Consistency Complete Report
SortSite Consistent No View Report

Changelog

This is the first version of this ACT rule.

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