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ChangeProposals/InstateLongdesc/References

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References


Requirements

Requirements

New Information

Recent Research has been conducted and new information collected. It includes:

HTML 4 on longdesc

  • HTML4 16.4.2 Long descriptions of frames: The longdesc attribute allows authors to make frame documents more accessible to people using non-visual user agents.
  • HTML4 Index of Attributes: longdesc "link to long description (complements alt)".
  • HTML4 longdesc = uri: "This attribute specifies a link to a long description of the image. This description should supplement the short description provided using the alt attribute. When the image has an associated image map, this attribute should provide information about the image map's contents. This is particularly important for server-side image maps. Since an IMG element may be within the content of an A element, the user agent's mechanism in the user interface for accessing the "longdesc" resource of the former must be different than the mechanism for accessing the href resource of the latter...The alt attribute provides a short description of the image. This should be sufficient to allow users to decide whether they want to follow the link given by the longdesc attribute to the longer description, here "sitemap.html".
  • HTML4 A.3 Changes for accessibility "Authors may provide long descriptions of tables, images, and frames (see the longdesc attribute)."

HTML5 on longdesc

longdesc is currently listed as an obsolete feature in the HTML5 editor's draft. It advises to "Use a regular a element to link to the description, or (in the case of images) use an image map to provide a link from the image to the image's description."

Web Content Accessibility Guidelines 2.0 on longdesc

User Agent Accessibility Guidelines 2.0 on longdesc

From the Implementing User Agent Accessibility Guidelines 2.0, Editors' Draft 11 March 2011:

3.1.2 Configurable Default Rendering: The user has a global option to specify which types of alternative content by default...

3.1.3 Browse and Render: The user can browse the alternatives, switch between them, and render them according to the following (Level A)...non-synchronized alternatives (e.g., short text alternatives, long descriptions) can be rendered as replacements for the original rendered content.

Open Publication Structure (OPS) on longdesc

  • Open Publication Structure (OPS) 2.0.1 - "For greater accessibility, it is strongly recommended that OPS Content Document authors include a URI reference in the optional longdesc attribute referencing a resource (such as another OPS Content Document in the Publication) describing the image in finer detail. Reading System developers are also strongly urged to recognize and render in an appropriate fashion (and with accessibility in mind) the resource specified in longdesc. For further information on the use of this attribute and related accessibility attributes, see http://www.w3.org/TR/1999/WAI-WEBCONTENT-19990505/#gl-provide-equivalents."
  • 3.30.3 longdesc - "Value should be a URI pointing to a long description, typically more detailed than, but complementary to, alt. Use of this attribute is strongly recommended because it can greatly enhance accessibility for print-disabled users."

Issue 30

Previous Proposals

Formal Objections to ISSUE 30 Decision

Request to Reopen HTML-ISSUE-30

Minutes

Related Bugs

  1. HTML Bug 10015: longdesc URL checking - Status RESOLVED WONTFIX.
  2. HTML Bug 10016: longdesc and @role (ARIA) - Status RESOLVED WONTFIX.
  3. HTML Bug 10017: longdesc and @aria-describedby (ARIA) - Status VERIFIED INVALID.
  4. HTML Bug 10019: Native user agent support for exposing longdesc to all users - Status RESOLVED WONTFIX.
  5. HTML Bug 10434: Mint a link type for pointing to long descriptions (rel="longdesc") - Status RESOLVED WORKSFORME.
  6. HTML Bug 10455: Mint a describedby attribute for the img element - Status RESOLVED WONTFIX.
  7. HTML Bug 10853: HTML5 lacks a verbose description mechanism - Status RESOLVED WONTFIX.
  8. HTML Bug 10967: Add @desclink, a description link attr. for any embedded element + figure - Status RESOLVED WONTFIX.
  9. HTML Bug 11012: Also say that <area>/image maps is an alternative to @longdesc - Status: RESOLVED FIXED.
  10. HTML Bug 12243 - Warn when ARIA-describedby/-labelledby points to interactive/form associated content - Status: NEW.
  11. HTML Bug 12363 - Include @longdesc in Microdata - Status: WONTFIX.

Glossary

Functional Replacement
A solution that provides the same utility that the current (longdesc) solution provides.
Programmatically Determinable
A long description needs to be programmatically determinable. This relates to the information in web content. If technologies that are accessibility supported are used properly, then assistive technologies and user agents can access the information in the content (i.e., programmatically determine the information in the content) and present it to the user. For instance longdesc as an attribute should be used as a hook by user agents and asssistive technologies in order to notify the user that a long description exists, so even if longdesc is applied to an image that also serves as a link, it is programmatically determinable to separate the activation of the longdesc for exposure from the UA's universal link activation action (which is usually activated with the ENTER key, the SpaceBar, or by mouse click), so that the linked image retains the expected behavior in response to user interaction while a discrete mechanism is used to retrieve the long description. HTML4 puts it this way, "Since an IMG element may be within the content of an A element, the user agent's mechanism in the user interface for accessing the 'longdesc' resource of the former must be different than the mechanism for accessing the href resource of the latter."
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