Proposed Test Rule: Heading is descriptive
Applicability
This rule applies to any semantic heading
element that is either visible or included in the accessibility tree.
Expectation 1
For each target element at least one of the following is true:
- the target element is not visible; or
- the target element describes the topic or purpose of the first palpable content which is non-decorative, visible, and after the target element in tree order in the flat tree.
Expectation 2
For each target element at least one of the following is true:
- the target element is not included in the accessibility tree; or
- the target element describes the topic or purpose of the first palpable content which is non-decorative, included in the accessibility tree, and after the target element in tree order in the flat tree.
Note: Headings do not need to be lengthy. A word, or even a single character, may suffice.
Assumptions
- This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.
- This rule assumes that the flat tree order is close to the reading order, as elements are rendered on the page. Due to positioning, it is possible to render a document in a order that greatly differ from the tree order, in which case the content which is visually associated with a heading might not be the content following it in tree order and this rule might fail while Success Criterion 2.4.6 Headings and Label is still satisfied.
Accessibility Support
Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some semantic heading
elements can fail this rule with some technology but users of other technologies would not experience any accessibility issue.
Background
Bibliography
- Understanding Success Criterion 2.4.6: Headings and Labels
- G130: Providing descriptive headings
- H42: Using h1-h6 to identify headings
- ARIA12: Using role=heading to identify headings
- HTML Specification - Heading content
Accessibility Requirements Mapping
2.4.6 Headings and Labels (Level AA)
- Learn more about 2.4.6 Headings and Labels
- Required for conformance to WCAG 2.0 and later on level AA and higher.
- Outcome mapping:
- Any
failed
outcomes: success criterion is not satisfied - All
passed
outcomes: success criterion needs further testing - An
inapplicable
outcome: success criterion needs further testing
- Any
Input Aspects
The following aspects are required in using this rule.
Test Cases
Passed
Passed Example 1
Heading marked up with h1
element that describes the topic or purpose of the following palpable content.
<html lang="en">
<h1>Opening Hours</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Passed Example 2
Heading marked up with role="heading"
that describes the topic or purpose of the following palpable content.
<html lang="en">
<span role="heading" aria-level="1">Opening Hours</span>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Passed Example 3
Heading marked up with role="heading"
that describes the topic or purpose of the following palpable content, with a default aria-level assigned.
<html lang="en">
<span role="heading">Opening Hours</span>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Passed Example 4
Heading marked up with h1
element with an image that describes the topic or purpose of the following palpable content.
<html lang="en">
<h1>
<img scr="/test-assets/descriptive-heading-b49b2e/opening_hours_icon.png" alt="Opening hours" />
</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Passed Example 5
Heading marked up with h1
element that is a single character that describes the topic or purpose of the following palpable content.
<html lang="en">
<h1>A</h1>
<dl>
<dt>airplane</dt>
<dd>
a powered flying vehicle with fixed wings and a weight greater than that of the air it displaces.
</dd>
<dt>apple</dt>
<dd>
the round fruit of a tree of the rose family, which typically has thin green or red skin and crisp flesh.
</dd>
</dl>
</html>
Passed Example 6
Heading marked up with role="heading"
that describes the topic or purpose of the following palpable content. The heading is positioned off screen and is included in the accessibility tree.
<html lang="en">
<span role="heading" aria-level="1" style="position: absolute; top: -9999px; left: -9999px;">Opening Hours</span>
<p style="position: absolute; top: -9999px; left: -9999px;">
We are open Monday through Friday from 10 to 16
</p>
</html>
Passed Example 7
Heading marked up with h1
element that describes the topic or purpose of the following palpable content. The heading is visible, but is not included in the accessibility tree.
<html lang="en">
<h1 aria-hidden="true">Opening Hours</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Passed Example 8
This heading describes the first palpable content after it (the first p
element). The next palpable content (the second p
element) is not considered by this rule.
<html lang="en">
<h1>Opening Hours</h1>
<p>We are open Monday through Friday from 10 to 16</p>
<p>We are open Saturday from 10 to 13</p>
</html>
Failed
Failed Example 1
Heading marked up with h1
element that does not describe the topic or purpose of the following palpable content.
<html lang="en">
<h1>Weather</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Failed Example 2
Heading marked up with role="heading"
that does not describe the topic or purpose of the following palpable content.
<html lang="en">
<span role="heading" aria-level="1">Weather</span>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Failed Example 3
Heading marked up with role="heading"
that does not describe the topic or purpose of the following palpable content. The heading is positioned off screen and is included in the accessibility tree.
<html lang="en">
<span role="heading" style="position: absolute; top: -9999px; left: -9999px;">Weather</span>
<p style="position: absolute; top: -9999px; left: -9999px;">
We are open Monday through Friday from 10 to 16
</p>
</html>
Failed Example 4
Heading marked up with h1
element that does not describe the topic or purpose of the following palpable content. The heading is visible, but is not included in the accessibility tree.
<html lang="en">
<h1 aria-hidden="true">Weather</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Failed Example 5
This heading does not describe the first palpable content after it (the first p
element). The next palpable content (the second p
element) is not considered by this rule.
<html lang="en">
<h1>Weather</h1>
<p>We are open Monday through Friday from 10 to 16</p>
<p>It is going to rain tomorrow</p>
</html>
Inapplicable
Inapplicable Example 1
No heading.
<html lang="en">
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Inapplicable Example 2
Heading that is neither visible to users, nor included in the accessibility tree.
<html lang="en">
<h1 style="display: none;">Opening hours</h1>
<p>We are open Monday through Friday from 10 to 16</p>
</html>
Inapplicable Example 3
Empty heading marked up with h1
is not visible.
<html lang="en">
<h1></h1>
</html>
Inapplicable Example 4
Empty heading marked up with role="heading"
is not visible.
<html lang="en">
<p role="heading" aria-level="1"></p>
</html>
Glossary
Explicit Semantic Role
The explicit semantic role of an element is determined by its role attribute (if any).
The role attribute takes a list of tokens. The explicit semantic role is the first valid role in this list. The valid roles are all non-abstract roles from WAI-ARIA Specifications. If the element has no role attribute, or if it has one with no valid role, then this element has no explicit semantic role.
Other roles may be added as they become available. Not all roles will be supported in all assistive technologies. Testers are encouraged to adjust which roles are allowed according to the accessibility support base line. For the purposes of executing test cases in all rules, it should be assumed that all roles are supported by assistive technologies so that none of the roles fail due to lack of accessibility support.
Focusable
Elements that can become the target of keyboard input as described in the HTML specification of focusable and can be focused.
Implicit Semantic Role
The implicit semantic role of an element is a pre-defined value given by the host language which depends on the element and its ancestors.
Implicit roles for HTML and SVG, are documented in the HTML accessibility API mappings (working draft) and the SVG accessibility API mappings (working draft).
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.
Marked as decorative
An element is marked as decorative if one or more of the following conditions is true:
- it has an explicit role of
none
orpresentation
; or - it is an
img
element with analt
attribute whose value is the empty string (alt=""
), and with no explicit role.
Elements are marked as decorative as a way to convey the intention of the author that they are pure decoration. It is different from the element actually being pure decoration as authors may make mistakes. It is different from the element being effectively ignored by assistive technologies as rules such as presentational roles conflict resolution may overwrite this intention.
Elements can also be ignored by assistive technologies if they are programmatically hidden. This is different from marking the element as decorative and does not convey the same intention. Notably, being programmatically hidden may change as users interact with the page (showing and hiding elements) while being marked as decorative should stay the same through all states of the page.
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:
- Inapplicable: No part of the test subject matches the applicability
- Passed: A test target meets all expectations
- Failed: A test target does not meet all expectations
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:
- has a
hidden
attribute; or - has a computed CSS property
display
ofnone
; or - has an
aria-hidden
attribute set totrue
Note: Contrarily to the other conditions, the visibility
CSS property may be reverted by descendants.
Semantic Role
The semantic role of an element is determined by the first of these cases that applies:
- Conflict If the element is marked as decorative, but the element is included in the accessibility tree; or would be included in the accessibility tree when it is not programmatically hidden, then its semantic role is its implicit role.
- Explicit If the element has an explicit role, then its semantic role is its explicit role.
- Implicit The semantic role of the element is its implicit role.
This definition can be used in expressions such as “semantic button
” meaning any element with a semantic role of button
.
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.
For more details, see examples of visible.
WAI-ARIA specifications
The WAI ARIA Specifications group both the WAI ARIA W3C Recommendation and ARIA modules, namely:
- Accessible Rich Internet Applications (WAI-ARIA) 1.1
- WAI-ARIA Graphics Module 1.0
- Digital Publishing WAI-ARIA Module 1.0
Note: depending on the type of content being evaluated, part of the specifications might be irrelevant and should be ignored.
Implementations
There are currently no known implementations for this rule. If you would like to contribute an implementation, please read the ACT Implementations page for details.
Changelog
This is the first version of this ACT rule.