RE: ACTION-1083: New note for alternative content, excluding fallback content

Proposed new note:
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Note 2: *Fallback content* is excluded from the definition of alternative content. The reason for this is that the format and nature of fallback content is too unpredictable to be relied upon as useful accessible alternative (e.g. the fallback content for a video could be an image with no alternative text).

Proposed new term:
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Fallback Content
Content that is to be used by the user agent when embedded content from an external resource cannot be used for some reason (e.g. the element is not supported, the resource is in an unsupported format, etc.).


Existing wording:
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alternative content
Web content that user agents can programmatically determine is usable in place of other content that some people are not able to access. Alternative content fulfills essentially the same function or purpose as the original content. There are several general types of alternative content:

- text alternative for non-text content: Text that is programmatically associated with non-text content or referred to from text that is programmatically associated with non-text content. For example, an image of a chart might have two text alternatives: a short text alternative and a described-by relationship to a nearby paragraph that more fully describes the content of the chart.
- alternative for time-based media: Web content that serves the same function or purpose as one or more tracks in a time-based media presentation. This includes alternatives for audio such as captions and sign language interpretation, and alternatives for video such as audio descriptions and extended audio descriptions. Another form of time-based media alternative is a correctly sequenced text description of time-based visual and auditory information that also is capable of achieving the outcomes of any interactivity in the time-based presentation.
- text alternatives for text content: Text that is programmatically associated with certain types of text content to provide expanded information. For example, an abbreviation (or acronym) can provide an expansion of the shortened word or initialized words (<abbr title="User Agent Accessibility Guidelines">UAAG</abbr>).
- media alternative for text: Media that presents no more information than is already presented in text (directly or via text alternatives). A media alternative for text is provided for people who benefit from alternate representations of text. Media alternatives for text can be audio-only, video-only (including sign-language video), or audio-video.

Note: According to WCAG 2.0, alternative content may or may not be programmatically determinable (e.g., a short description for an image might appear in the image's description attribute or within text near the image). However, UAAG 2.0 adds the programmatically available condition because this is the only type of alternative content that user agents can recognize. 



(MR) JAN RICHARDS
PROJECT MANAGER
INCLUSIVE DESIGN RESEARCH CENTRE (IDRC)
OCAD UNIVERSITY

T 416 977 6000 x3957
F 416 977 9844
E jrichards@ocadu.ca

________________________________________
From: User Agent Accessibility Guidelines Working Group Issue Tracker [sysbot+tracker@w3.org]
Sent: April-09-15 2:25 PM
To: w3c-wai-ua@w3.org
Subject: ACTION-1083: New note for alternative content, excluding fallback content

ACTION-1083: New note for alternative content, excluding fallback content

http://www.w3.org/WAI/UA/tracker/actions/1083

Assigned to: Jan Richards

Received on Thursday, 9 April 2015 19:04:29 UTC