Providing a long description in another location with a link to it that is immediately adjacent to the non-text content

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.1 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.1.

Applicability

Applies to all technologies

This technique relates to Success Criterion 1.1.1: Non-text Content (Sufficient).

Description

The objective of this technique is to provide a way to link to remote long descriptions in technologies that do not have a long description feature built directly into them (e.g., longdesc) or where the feature is known to not be supported.

With this technique, the long description is provided in another location than the non-text content. This could be at another location within the same URI or at another URI. A link to that long description is provided that is immediately adjacent to the non-text content. The link can be immediately before or after the non-text content. If the description is located along with other text then put "End of description" at the end so that they know when to stop reading and return to the main content. If a "Back" button will not take the person back to the point from which they jumped, then a link back to the non-text content location is provided.

This technique was commonly used in HTML before 'longdesc' was added to the specification. In HTML it was called a D-Link because it was usually implemented by putting a D next to images and using the D as a link to the long description. This technique is not technology specific and can be used in any technology that supports links.

Examples

Example 1: Bar chart

There is a bar chart on a Web page showing the sales for the top three salespeople.

The short text alternative says "October sales chart for top three salespeople."

Immediately after the non-text content is a small image denoting a long description. The alternate text for the image is "Long description of chart". The image links to the bottom of the page where there is a section titled "Description of charts on this page". The link points to this specific description: "Sales for October show Mary leading with 400 units. Mike follows closely with 389. Chris rounds out our top 3 with sales of 350. [end of description]"

Example 2: Bar chart - in non-HTML technology where user agent "back" is not supported for security reasons.

There is a bar chart on a Web page showing the sales for the top three salespeople.

The short text alternative says "October sales chart for top three salespeople."

Immediately after the non-text content is a small image denoting the long description. The alternate text for the image is "Long description of chart". The image links to another page titled "Description of charts in October Sales Report". The description link points to this specific description: "Sales for October show Mary leading with 400 units. Mike follows closely with 389. Chris rounds out our top 3 with sales of 350. End of description. <link>Back to Sales Chart</link>"

Example 4: Transcript of an audio-only file

There is a recording of a speech by Martin Luther King. Links to the audio file and the transcript appear side by side.

Tests

Procedure

  1. check for the presence of a link immediately before or after the non-text content
  2. check that the link is a valid link that points directly to the long description of this particular non-text content.
  3. check that the long description conveys the same information as the non-text content
  4. check for the availability of a link or back function to get the user back to the original location of the non-text content

Expected Results

All 4 of the above are true