[ttml2] Ensure that it is possible to extract plain text

nigelmegitt has just created a new issue for 
https://github.com/w3c/ttml2:

== Ensure that it is possible to extract plain text ==
See the text just above 
https://www.w3.org/2015/10/28-tt-minutes.html#action03 for context.

Especially where relatively complex syntax is needed for correct 
presentation of text, for example nested spans, Rubys, temporal order 
differing from document order etc, it needs to be clear how to extract
 the plain text content from a TTML2 document instance - this is 
useful for accessibility purposes for example.

Possible (non-exclusive) solutions:
* define an algorithm for extracting content that clarifies the order 
of precedence of time vs document
* add a new entry for the `ttm:role` attribute of 
`"presentation-enhancement"` to allow such content to be filtered out 
- e.g. to exclude spans for rubys
* incorporate one or more of the WAI-ARIA roles such as "main" via 
either the existing role attribute or a new one with a different name.

Please view or discuss this issue at 
https://github.com/w3c/ttml2/issues/151 using your GitHub account

Received on Friday, 4 March 2016 12:19:00 UTC