| id | bf051a | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| name | HTML page lang attribute has valid language tag | ||||||||||||||||||||
| rule_type | atomic | ||||||||||||||||||||
| description | This rule checks that the `lang` attribute of the root element of a non-embedded HTML page has a language tag with a known primary language subtag. | ||||||||||||||||||||
| accessibility_requirements |
|
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| input_aspects |
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| acknowledgments |
|
This rule applies to any document element if it is an html element for which all the following are true:
- has a
langattribute that is neither empty ("") nor only ASCII whitespace; and - is in a top-level browsing context; and
- has a node document with a content type of
text/html.
For each test target, the lang attribute has a known primary language tag.
-
The language of the page can be set by other methods than the
langattribute, for example using HTTP headers or themetaelement. These methods are not supported by all assistive technologies. This rule assumes that these other methods are insufficient to satisfying Success Criterion 3.1.1: Language of Page. -
This rule assumes that user agents and assistive technologies can programmatically determine known primary language tags even if these do not conform to the RFC 5646 syntax.
-
This rule assumes that only known primary language tags are enough to satisfy Success Criterion 3.1.1 Language of Page; this notably excludes grandfathered tags and ISO 639.2 three-letters codes, both having poor support in assistive technologies.
There are no accessibility support issues known.
This rule is only applicable to non-embedded HTML pages. HTML pages embedded into other documents, such as through iframe or object elements are not applicable because they are not web pages according to the definition in WCAG.
- Understanding Success Criterion 3.1.1: Language of Page
- H57: Using language attributes on the html element
- RFC 5646: Tags for Identifying Languages
- The
langandxml:langattributes
This html element has a lang attribute with a known primary language tag.
<html lang="FR"></html>This html element has a lang attribute with a known primary language tag even though the region subtag is not.
<html lang="en-US-GB"></html>This html element has a lang attribute with a known primary language tag.
<html lang="em-US"></html>This html element has a lang attribute with a known primary language tag.
<html lang="#1"></html>The lang attribute of this page is an iso 639.2 three letters code, which has no known primary language tag.
<html lang="eng">
<body>
<p lang="en">I love ACT rules!</p>
</body>
</html>The lang attribute of this page is a grandfathered tag, which has no known primary language tag.
<html lang="i-lux">
<body>
<p lang="lb">Lëtzebuerg ass e Land an Europa.</p>
</body>
</html>This rule does not apply to svg elements.
<svg xmlns="http://www.w3.org/2000/svg" lang="fr"></svg>Details
## Boundary ExamplesThese examples are not normative and not require for consistent implementations. They illustrate limitations and boundaries of the rule. Passed and Inapplicable examples in this category are likely to fail the rule's accessibility requirement, showing how the rule is only a partial test. Testing tools and methodologies are encouraged to be more clever than the rule, and to report the correct outcome for these examples. Therefore, they are not required for consistent implementation.
This html element has an empty lang attribute. It is not applicable for this rule, but nonetheless fails Success Criterion 3.1.1 Language of Page. It also fails rule HTML page has lang attribute.
<html lang="">
<body>
I love ACT rules.
</body>
</html>