Link in context is descriptive

  • Rule Type:atomic
  • Rule Id: 5effbb
  • Last modified: Sep 16, 2021
  • Accessibility Requirements Mapping:
    • 2.4.4 Link Purpose (In Context) (Level A)
      • Learn More about 2.4.4 Link Purpose (In Context)
      • Required for conformance to WCAG 2.0 and later on level A 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.
    • 2.4.9 Link Purpose (Link Only) (Level AAA)
      • Learn More about 2.4.9 Link Purpose (Link Only)
      • Required for conformance to WCAG 2.0 and later on level AAA.
      • 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.

Description

This rule checks that the accessible name of a link together with its context describes its purpose.

Applicability

This rule applies to any inheriting semantic link for which all the following is true:

Expectation

The accessible name of each target element together with its programmatically determined link context describes the purpose of the link.

Assumptions

  • This rule assumes that the purpose of the link is not ambiguous to users in general when seen in context on the web page, which is the exception mentioned in success criteria 2.4.4 Link Purpose (In Context) or 2.4.9 Link Purpose (Link only). If the link is ambiguous to users in general, users of assistive technologies are not at a disadvantage when viewing the link out of context.
  • This rule assumes that all semantic link elements are used as links. An element marked up as a link, but that does not behave as a link would not fail success criteria 2.4.4 Link Purpose (In Context) or 2.4.9 Link Purpose (Link only).
  • This rule assumes that the language of each test target can be correctly determined (either programmatically or by analyzing the content), and sufficiently understood.

Accessibility Support

  • Implementation of Presentational Roles Conflict Resolution varies from one browser or assistive technology to another. Depending on this, some semantic link elements can fail this rule with some technology but users of other technologies would not experience any accessibility issue.

Background

This rule is designed specifically for 2.4.4 Link Purpose (In Context), which requires the purpose to be clear within the context of a link. Because links that do not have this, also are not clear without that context, this rule maps to 2.4.9 Link Purpose (Link only) as well. In order to adequately test the expectation, some of the passed examples do not satisfy 2.4.9 Link Purpose (Link only).

Test Cases

Passed

Passed Example 1

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The accessible name (from the link's text) describes the purpose of the link.

<a href="#desc">See the description of this product.</a>

<p id="desc">This product consists of several web pages.</p>

Passed Example 2

Open in a new tab

The accessible name describes the purpose of the link.

<a href="#main"><img src="/test-assets/5effbb/main.png" alt="Go to the main content"/></a>

<main>
	<p id="main">This is the main content.</p>
</main>

Passed Example 3

Open in a new tab

The accessible name (from the link's text), together with its programmatically determined link context (available from the text in the closest p ancestor), describes the purpose of the link.

<p>See the description of <a href="#desc">this product</a>.</p>

<p id="desc">This product consists of several web pages.</p>

Passed Example 4

Open in a new tab

The accessible name (from the link's text) describes the purpose of the link.

<span role="link" tabindex="0" onclick="document.location+='#desc'">See description of the product.</span>

<p id="desc">This product consists of several web pages.</p>

Passed Example 5

Open in a new tab

The programmatically determined link context (provided by the ancestor with a role of listitem and text "Ulysses") and the accessible name (from the link's text) describe the purpose of the links.

<ul>
	<li>
		Ulysses
		<ul>
			<li><a href="https://www.gutenberg.org/files/4300/4300-h/4300-h.htm"> HTML </a></li>
			<li>
				<a href="https://www.gutenberg.org/ebooks/4300.epub.images?session_id=04cd710372888de8d8d322215cdfe8ce5b0f8d73">
					EPUB
				</a>
			</li>
			<li><a href="https://www.gutenberg.org/files/4300/4300-0.txt"> Plain text </a></li>
		</ul>
	</li>
</ul>

Passed Example 6

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The programmatically determined link context (provided by the table header assigned to the cell containing the link) and the accessible name (from the link's text) describe the purpose of the links.

<table>
	<tr>
		<th colspan="3">Ulysses</th>
	</tr>
	<tr>
		<td><a href="https://www.gutenberg.org/files/4300/4300-h/4300-h.htm">HTML</a></td>
		<td>
			<a href="https://www.gutenberg.org/ebooks/4300.epub.images?session_id=04cd710372888de8d8d322215cdfe8ce5b0f8d73"
				>EPUB</a
			>
		</td>
		<td><a href="https://www.gutenberg.org/files/4300/4300-0.txt">Plain text</a></td>
	</tr>
</table>

Passed Example 7

Open in a new tab

The accessible name describes the purpose of the link.

<p id="instructions">Go to the main content.</p>
<svg xmlns="http://www.w3.org/2000/svg" x="0" y="0">
	<a href="#main" aria-labelledby="instructions">
		<path
			style="fill:#1E201D;"
			d="M21.205,5.007c-0.429-0.444-1.143-0.444-1.587,0c-0.429,0.429-0.429,1.143,0,1.571l8.047,8.047H1.111
			C0.492,14.626,0,15.118,0,15.737c0,0.619,0.492,1.127,1.111,1.127h26.554l-8.047,8.032c-0.429,0.444-0.429,1.159,0,1.587
			c0.444,0.444,1.159,0.444,1.587,0l9.952-9.952c0.444-0.429,0.444-1.143,0-1.571L21.205,5.007z"
		/>
	</a>
</svg>

<main>
	<p id="main">This is the main content.</p>
</main>

Passed Example 8

Open in a new tab

The programmatically determined link context (provided by the cell containing the link) and the accessible name (from the link's text) describe the purpose of the links.

<table>
	<tr>
		<td>
			Download Ulysses in
			<a href="https://www.gutenberg.org/files/4300/4300-h/4300-h.htm">HTML</a>
		</td>
		<td>
			Download Ulysses in
			<a href="https://www.gutenberg.org/ebooks/4300.epub.images?session_id=04cd710372888de8d8d322215cdfe8ce5b0f8d73"
				>EPUB</a
			>
		</td>
	</tr>
</table>

Passed Example 9

Open in a new tab

The programmatically determined link context (provided by the element referenced by the aria-describedby attribute) and the accessible name (from the link's text) describe the purpose of the links.

<h2 id="rule">Button has accessible name</h2>
<ul>
	<li><a href="https://act-rules.github.io/rules/97a4e1#applicability" aria-describedby="rule">Applicability</a></li>
	<li><a href="https://act-rules.github.io/rules/97a4e1#expectation" aria-describedby="rule">Expectation</a></li>
</ul>

Failed

Failed Example 1

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The accessible name (from the link's text), together with the absence of programmatically determined link context, does not describe the purpose of the link.

<a href="#desc">More</a>

<p id="desc">This product consists of several web pages.</p>

Failed Example 2

Open in a new tab

The accessible name (from the link's text), together with the absence of programmatically determined link context, does not describe the purpose of the link.

<div role="link" tabindex="0" onclick="document.location+='#main'">More</div>

<main>
	<p id="main">This is the main content.</p>
</main>

Failed Example 3

Open in a new tab

The accessible name (from the link's text), together with the absence of programmatically determined link context, does not describe the purpose of the link.

<svg xmlns="http://www.w3.org/2000/svg" x="0" y="0">
	<a href="#main">
		<text x="20" y="20">
			Go
		</text>
	</a>
</svg>

<main>
	<p id="main">This is the main content.</p>
</main>

Failed Example 4

Open in a new tab

The accessible name (from the link's text) does not describe the purpose of the link. The other information available on the page is not programmatically determined link context because it is in a different p element.

<p>
	The W3C held a workshop on June 9-10, 2005 at DERI Innsbruck (Austria), to gather information about potential
	standardization work on Semantics in Web Services.
</p>

<p><a href="https://www.w3.org/2005/04/FSWS/workshop-report.html">Workshop</a></p>

Failed Example 5

Open in a new tab

The accessible name (from the link's text) does not describe the purpose of the link. The other information available on the page is not programmatically determined link context because it is outside the list where the links are.

<p style="font-weight: bold">Ulysses</p>
<ul>
	<li><a href="https://www.gutenberg.org/files/4300/4300-h/4300-h.htm"> HTML </a></li>
	<li>
		<a href="https://www.gutenberg.org/ebooks/4300.epub.images?session_id=04cd710372888de8d8d322215cdfe8ce5b0f8d73">
			EPUB
		</a>
	</li>
	<li><a href="https://www.gutenberg.org/files/4300/4300-0.txt"> Plain text </a></li>
</ul>

Failed Example 6

Open in a new tab

The accessible name (from the link's text) does not describe the purpose of the link. The other information available on the page is not programmatically determined link context because it not available on the same cell of the link or in a header cell for that cell.

<table>
	<tr>
		<th colspan="3">Books</th>
	</tr>
	<tr>
		<td>Ulysses</td>
		<td><a href="https://www.gutenberg.org/files/4300/4300-h/4300-h.htm">Download</a></td>
		<td>1.61MB</td>
	</tr>
</table>

Inapplicable

Inapplicable Example 1

Open in a new tab

An a element with its semantic role changed from link to another role.

<a href="https://www.w3.org/WAI" role="button">Web Accessibility Initiative (WAI)</a>

Inapplicable Example 2

Open in a new tab

The link element is not included in the accessibility tree.

<a href="https://www.w3.org/WAI" style="display: none;"
	><img src="/test-assets/5effbb/cart.svg" alt="Checkout" />Checkout</a
>

Inapplicable Example 3

Open in a new tab

This a element is not a semantic link, because it has no href attribute.

<a>placeholder</a>

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.

Accessibility Support for Accessible Name

  • Because the accessible name and description computation is not clear about which whitespace are considered, browsers behave differently when trimming and flattening the accessible name. For example, some browsers completely trim non-breaking spaces while some keep them in the accessible name.
  • There exists a popular browser which does not perform the same trimming and flattening depending whether the accessible name comes from content, an aria-label attribute, or an alt attribute.
  • There exists a popular browser which assign no accessible name (null) when none is provided, instead of assigned an empty accessible name ("").
  • The accessible name and description computation suggest that if an aria-labelledby attribute refers to an existing but empty element, the computation should stop and return an empty name without defaulting to the next steps. Several user agents and assistive technologies chose to use the next step in the computation in this case.

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.

Accessibility Support for Explicit Semantic Role

Some browsers and assistive technologies treat the tokens of the role attribute as case-sensitive. Unless lowercase letters are used for the value of the role attribute, not all user agents will be able to interpret the tokens correctly. ARIA in HTML (working draft) also specifies that authors must use lowercase letters for the role and aria-* attributes.

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).

Accessibility Support for Implicit Semantic Role

  • Images with an empty alt attribute should have an implicit role of presentation, according to the HTML Accessibility API Mapping (work in progress). However, there are several popular browsers that do not treat images with empty alt attribute as having a role of presentation. Instead, they add the img element to the accessibility tree with a role of either img or graphic.

Included in the accessibility tree

Elements included in the accessibility tree of platform specific accessibility APIs. Elements in the accessibility tree are exposed to assistive technologies, allowing users to interact with the elements in a way that meet 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][].

Note: Users of assistive technologies might still be able to interact with elements that are not included in the accessibility tree. An example of this is a focusable element with an aria-hidden attribute with a value of true. Such an element could still be interacted using sequential keyboard navigation regardless of the assistive technologies used, even though the element would not be included in the accessibility tree. [examples of included in the accessibility tree]: https://act-rules.github.io/pages/examples/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 or presentation; or
  • it is an img element with an alt 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 Determined Link Context

The programmatically determined context of a link (or programmatically determined link context) is the set of all elements that are included in the accessibility tree, and have one or more of the following relationships to the link:

This definition is based on the WCAG definition of programmatically determined link context.

This definition assumes that the HTML document with the link is a document using HTML according to the specification.

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 of none; or
  • has an aria-hidden attribute set to true

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:

  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.

Accessibility Support for Definition of Semantic Role for Semantic Role

  • There exist popular web browsers and assistive technologies which do not correctly implement Presentational Roles Conflict Resolution. These technologies will not include in the accessibility tree elements that should be, according to Specifications. Thus, some elements that should have their semantic role fixed by case Conflict above are instead falling into case Explicit and are hidden for users of assistive technologies.
  • A similar conflict exists for focusable elements with a aria-hidden="true" attribute. The WAI ARIA specification does not explain how to solve it. Some browsers give precedence to the element being focusable (and expose it in the accessibility tree) while some give precedence to the aria-hidden attribute (and hide the element).

Useful Links


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. This section will not be included in the rule when it is published on the W3C website.

ToolConsistencyCompleteReport
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Acknowledgments

Funding

  • WAI-Tools
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