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HTML page has lang attribute


This rule checks that an HTML page has a non-empty lang attribute.


This rule applies to any document element if it is an html element for which all the following are true:

Note: html elements within iframe and object elements are not applicable as iframe and object elements create nested browsing contexts. However, as these elements are meant to provide a layer of isolation, the declared language of their parent browsing context will likely not be inherited, making it possible for empty lang attributes in nested browsing contexts to also cause accessibility issues.


Each test target has a lang attribute value that is neither empty ("") nor only ASCII whitespace.


The language of the page can be set by other methods than the lang attribute, for example using HTTP headers or the meta element. 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.

Accessibility Support

There are no major accessibility support issues known for this rule.



Accessibility Requirements Mapping

Input Aspects

The following aspects are required in using this rule.

Test Cases


Passed Example 1

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This html element has a lang attribute with a non-empty ("") value.

<html lang="en"></html>


Failed Example 1

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This html element does not have a lang attribute.


Failed Example 2

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This html element has a lang attribute with an empty ("") value.

<html lang=""></html>

Failed Example 3

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This html element has a lang attribute whose value is only ASCII whitespace.

<html lang=" "></html>

Failed Example 4

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This html element has no lang attribute, only a xml:lang attribute.

<html xml:lang="en"></html>


Inapplicable Example 1

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This rule does not apply to an svg element.

<svg xmlns=""></svg>

Inapplicable Example 2

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This rule does not apply to a math element.



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.


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.

Rule Versions

  1. Proposed version, 21 June 2022 (compare)
  2. Latest version, 28 January 2022


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 Type Consistency Report
Alfa (fully automated) 0.57.2 Automated tool Consistent Alfa (fully automated) Report
Alfa (semi-automated) 0.57.2 Semi-automated tool Consistent Alfa (semi-automated) Report
Axe DevTools Pro 4.37.1 Semi-automated tool Consistent Axe DevTools Pro Report
Axe-core 4.6.0 Automated tool Consistent Axe-core Report
Equal Access Accessibility Checker 3.1.42-rc.0 Automated tool Consistent Equal Access Accessibility Checker Report
QualWeb 3.0.0 Automated tool Consistent QualWeb Report
SortSite 6.45 Automated tool Consistent SortSite Report
Trusted Tester 5.1 Test methodology Consistent Trusted Tester Report
ember-template-lint 5.5.1 Linter Consistent ember-template-lint Report
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