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Proposed Heading is descriptive

Description

This rule checks that headings describe the topic or purpose of the content.

Applicability

This rule applies to any semantic heading element that is included in the accessibility tree and has a non-empty (””) accessible name.

Expectation

Each target element describes the topic or purpose of the first perceivable content after the test target that is not decorative. The order of elements is determined by the flat tree.

Note: Headings do not need to be lengthy. A word, or even a single character, may be sufficient.

Assumptions

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 an order that greatly differs 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.

This rule also assumes that the content the heading is intended to describe is visible and not hidden from assistive technologies. Otherwise, cases such as expandable content using a heading might fail this rule 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

Headings that are visible but not in the accessibility tree are a failure of Success Criterion 1.3.1 Info and Relationships. These are not tested by this rule but they can still fail Success Criterion 2.4.6 Headings and Labels.

Bibliography

Accessibility Requirements Mapping

Input Aspects

The following aspects are required in using this rule.

Test Cases

Passed

Passed Example 1

Open in a new tab

This h1 heading element describes the topic of the following paragraph.

<html lang="en">
	<h1>Opening Hours</h1>
	<p>We are open Monday through Friday from 10 to 16</p>
</html>

Passed Example 2

Open in a new tab

This heading marked up with an explicit role of heading describes the topic of the following paragraph.

<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

Open in a new tab

This h1 heading element with an image describes the topic of the following paragraph.

<html lang="en">
	<h1>
		<img src="/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 4

Open in a new tab

This h1 heading element has a single character text that describes the topic of the following description list.

<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 5

Open in a new tab

This heading marked up with an explicit role of heading describes the topic of the following paragraph. The heading is positioned off screen but 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>
		We are open Monday through Friday from 10 to 16
	</p>
</html>

Passed Example 6

Open in a new tab

This heading describes the first perceivable content after it (the first p element). The next perceivable 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

Open in a new tab

This h1 heading element does not describes the topic of the following paragraph.

<html lang="en">
	<h1>Weather</h1>
	<p>We are open Monday through Friday from 10 to 16</p>
</html>

Failed Example 2

Open in a new tab

This heading marked up with an explicit role of heading does not describe the topic of the following paragraph.

<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

Open in a new tab

This heading marked up with an explicit role of heading does not describe the topic of the following paragraph. The heading is positioned off screen but is included in the accessibility tree.

<html lang="en">
	<span role="heading" aria-level="1" style="position: absolute; top: -9999px; left: -9999px;">Weather</span>
	<p>
		We are open Monday through Friday from 10 to 16
	</p>
</html>

Failed Example 4

Open in a new tab

This h1 heading element does not describe the first perceivable content after it (the first p element). The next perceivable 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

Open in a new tab

There is no heading.

<html lang="en">
	<p>We are open Monday through Friday from 10 to 16</p>
</html>

Inapplicable Example 2

Open in a new tab

This h1 heading element is not included in the accessibility tree.

<html lang="en">
	<h1 hidden>Opening Hours</h1>
	<p>We are open Monday through Friday from 10 to 16</p>
</html>

Inapplicable Example 3

Open in a new tab

This h1 heading element has an empty accessible name.

<html lang="en">
	<h1></h1>
</html>

Inapplicable Example 4

Open in a new tab

Semantic heading has an empty accessible name.

<html lang="en">
	<p role="heading" aria-level="1"></p>
</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.

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

An element is focusable if one or both of the following are true:

Exception: Elements that lose focus during a period of up to 1 second after gaining focus, without the user interacting with the page the element is on, are not considered focusable.

Notes:

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:

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:

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.

Perceivable content

A node is perceivable content if all the following are true:

Perceivable content corresponds to nodes that contain information and are perceived by some categories of users.

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

Note: The HTML standard suggests setting the CSS display property to none for elements with the hidden attribute. While not required by HTML, all modern browsers follow this suggestion. Because of this the hidden attribute is not used in this definition. In browsers that use this suggestion, overriding the CSS display property can reveal elements with the hidden attribute.

Semantic Role

The semantic role of an element is determined by the first of these cases that applies:

  1. 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.
  2. Explicit If the element has an explicit role, then its semantic role is its explicit role.
  3. 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.

Content is defined in WCAG.

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:

Note: depending on the type of content being evaluated, part of the specifications might be irrelevant and should be ignored.

Rule Versions

This is the first version of this ACT rule.

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 Type Consistency Report
Trusted Tester 5.1 Test methodology Consistent Trusted Tester Report
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