PF/XTech/HTML5/TextAlternativeProposal

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Text Alternative Proposal (Collaborative March 4-6, 2009 version)

FINAL RESOLUTIONS

Composite Proposal / Resolutions

This version is a collaborative of previous related proposals.

General RESOLUTIONS

NOTING THAT:

  • @alt is a very important accessibility attribute (it is supported by all browsers, most authoring tools and is the most well known accessibility technique among authors).
  • Having @alt "required" in HTML 4.01 raised public awareness of Web accessibility in general.
  • automatic validators can detect the presence/absence of @alt but in general can't certify the correctness of the text string.

RESOLUTION 1: We agree HTML5 should provide mechanism(s) for providing short text alternatives.

RESOLUTION 2: We agree HTML5 should provide mechanism(s) for providing long text alternatives.

RESOLUTION 3: We agree HTML5 should provide mechanisms to allow both short and long text alternatives at the same time.

RESOLUTION 4: We recommend continued inclusion of the "alt" attribute as a non-deprecated mechanism to provide short text alternatives.

RESOLUTION 5: That HTML5 state that "For guidance on accessibility requirements for text alternatives authors SHOULD consult WCAG 2.0." and that HTML should not provide any guidance that conflicts with WCAG.

RESOLUTIONS REGARDING Short alternatives

  1. IMG is only valid under any of the following conditions:
    • alt is present (empty or non-empty)
    • aria-labelledby is present (non-empty only)
    • role="presentation"
    • the IMG is located within a FIGURE that has a non-empty LEGEND
  2. That the proper use of @role="presentation" be taken from ARIA 1.0 and that an IMG without a @role attribute is assumed to be the equivalent of <IMG @role="img"> (and would follow the rules in #1 above)
  3. For cases in which it is appropriate for user agents to ignore the presence of the image (e.g., when they are used for decoration, formatting, or are invisible), one or both of the following may be used:
    • @role="presentation"
    • alt="" (also see (4))
  4. alt="" WITHOUT an accompanying role="presentation" triggers a non-critical validator warning recommending use of role="presentation" (but alt="" remains technically valid)
  5. We suggest new mechanisms for short text alternatives (e.g. labelledby, LEGEND) should be capable of handling structured content. Our primary concern is that short text alternatives be able to support inline text structure, such as abbreviations, language changes, emphasis, etc.

RELATED RECOMMENDATIONS TO WCAG

NOTE: The following recommendations are being passed on to WCAG working group to be developed into techniques. They are provided here for background and context.

  • If (and only if) an image is broken up into pieces that are intended to be perceived as one image the text alternative for the _composite image_ can be for the first image with the other pieces marked as presentational. This does not apply to a series of pictures.
  • To provide a short descriptor for a collection of images contained in a FIGURE, LEGEND can be used to provide a short description of the varied images. If the LEGEND is used for something other than a short description then alt or labelledby needs to be specified for each image.

RESOLUTIONS REGARDING Long text alternatives (that go beyond short text alternatives)

  1. Long text alternatives (e.g. describedby ) (to supplement short text alternatives) are not required for validity (though they may be required by WCAG 2.0 for conformance for some types of non-text content).
  2. Mechanism(s) for long text alternatives should be capable of handling structured content.
    • Our primary concern with long text alternatives is that they be able to support block and inline text structure, such as abbreviations, language changes, emphasis, tables, headings, etc. However it is not necessarily limited to these and could include rich media types.
  3. Because we assume that aria-describedby will be supported by AT at least as well as longdesc when HTML5 goes to Rec
    • IF
      • aria-describedby is incorporated in HTML5
      • and describedby allows pointing to long text alternatives off of the page (by pointing to a link on the page)
  4. THEN
    • we believe it is acceptable to make longdesc deprecated in HTML5.

END OF RECOMMENDATIONS


OLDER NOTES AND MEETING MINUTES

Meetings and Resolutions

February 4 Special WAI CG meeting on HTML alt

February 4, 2009 Minutes

    proposal: @alt is a very important accessibility attribute (it is supported by all browsers, most authoring tools and is the most well known accessibility technique among authors).
    PROP: Having @alt "required" in HTML 4.01 raised public awareness of Web accessibility in general.
    PROP: automatic validators can detect the presence/absence of @alt but in general can't certify the correctness of the text string.
    We want HTML5 to provide mechanisms for providing text alternatives.
    RESOLUTION: We agree all guidance on the the content of @alt, including any examples that are provided in HTML5 to be non-normitive and be provided in coordinations with the WAI PF WG.  

February 12 Special WAI CG meeting on HTML alt

February 12, 2009 Minutes

    RESOLUTION: We agree HTML5 should provide mechanism(s) for providing short text alternatives.
    RESOLUTION: We agree HTML5 should provide mechanism(s) for providing long text alternatives.
    RESOLUTION: We agree HTML5 should provide mechanisms to provide both short andlong text alternatives at the same time.
    RESOLUTION: We agree mechanism(s) for long text alternatives should be capable of handling structured content.
    RESOLUTION: We suggest new mechanisms for short text alternatives should be capable of handling structured content ... Our primary concern with short text alternatives is that they be able to inline support text structure, such as abbreviations, language changes, emphasis, etc.  ... Our primary concern with long text alternatives is that they be able to support block and inline text structure, such as abbreviations, language changes, emphasis, tables, headings, etc.
    RESOLUTION: We recommend continued inclusion of the "alt" attribute as a non-deprecated mechanism to provide short text alternatives.
    RESOLUTION: Because we believe aria-describedby will be supported by AT at least as well as longdesc when HTML5 goes to Rec, we believe it is acceptable to make longdesc obsolete in HTML5

March 4 Special WAI CG meeting on HTML alt

March 4, 2009 Minutes

March 6 Special WAI CG meeting on HTML alt

March 6, 2009 Minutes


Previous Related Proposals

EITHER:

  • A. That alt="" is valid ONLY when role="presentation".
  • B. That alt="" is valid ONLY when role="presentation". An IMG without a role attribute is the equivalent of <IMG aria-role="image"> and REQUIRES the use of alt, labelledby, and/or LEGEND for validity. For guidance as to what constitutes a valid text alternative for the purpose of disability access consult WCAG 2.0.
  • C. That alt="" WITHOUT an accompanying role="presentation" MUST trigger a non-critical validity warning (but is still valid).
  • D. That alt="" is valid ONLY when role="presentation" (or role="presentation" would be appropriate if role is not used). alt="" with any role besides "presentation" MUST trigger a validity error.
  • E. Other ideas?

Sample Code

Three Stages of A Butterfly's Life Example

Each of the images in the 3 stages of a butterfly's life REQUIRE alt text and/or labelledby to provide them with unique and appropriate short descriptions, just as each form control in a FIELDSET has its own LABEL defined for it, with the value of the LEGEND element providing a CAPTION-like function for the FIELDSET, so too does LEGEND provide a means of declaratively marking explicit bindings of groups of related objects, as in:


 
<FIGURE aria-labelledby="l1">
<LEGEND id="l1">The Three Stages of a Butterfly's Life Cycle</LEGEND>
<IMG alt="Stage 1: The larval stage." src="butterfly1.svg" 
     longdesc="butterfly1.html">
<IMG alt="Stage 2: The pupal stage." src="butterfly2.svg" 
     longdesc="butterfly2.html">
<IMG alt="Stage 3: The adult stage." src="butterfly3.svg" 
     longdesc="butterfly3.html">
</FIGURE>
 


the LEGEND applies to all three images as a collection of related objects, available, for example, in a screen reader situation, either through a verbosity setting or via an extended query, such as MagicKey+TAB reads the alt text of the individual graphic which has focus, MagicKey+TAB pressed twice rapidly (or with a moderator key) provides the user with the LEGEND which describes, tersely, the group to which the individual image belongs, so that the user can be made aware of:

a) each individual image's short alternative text;

b) the grouping to which the image belongs (if it is one of a series presented in a FIGURE) or any other modality-specific content contained in HTML5's media-specific elements, including AUDIO, VIDEO, OBJECT and CANVAS;

Related Resources


BONEYARD

1. That HTML5 validity REQUIRE short text alternatives for non-text items that are not presentational and that these be provided using one of the HTML5 specified methods: (alt, labelledby, or legend).

  • For example
    • For images; alt attribute or aria-labelledby can be used.
    • For an image that is a child of a figure; alt attribute, aria-labelledby, or legend can be used (would be valid).
    • (this would apply to other non-text content as well)
  • That the proper use of role="presentation" be taken from ARIA 1.0.
  • An IMG without a role attribute is the equivalent of <IMG aria-role="image"> and REQUIRES the use of alt, labelledby, and/or LEGEND for validity.
  • The following applies to alt="" and validity.
    • That for content where role="presentation" is appropriate either alt="" or role="presentation" or both can be used.
      • That alt="" WITHOUT an accompanying role="presentation" would trigger a non-critical warning recommending use of role="presentation" (but is still valid).