No, it'll likely be considered for the next revision to work around the lack of @longdesc (assuming that stays true), but is not an official part of the specification at this time. There is an open issue in the tracker to deal with this problem.
There is currently a draft document for potential inclusion in ARIA 1.1. Members of the DIAGRAM working group have been working to prepare an EPUB equivalent that can be presented for consideration during the next EPUB revision so we don't have to wait on the next ARIA revision cycle to be able to include out-of-band descriptions, which is where that attribute comes from. It is documented in the content guidelines, with a big red warning at the top, only as a future-looking option.
No, it'll likely be considered for the next revision to work around the lack of @longdesc (assuming that stays true), but is not an official part of the specification at this time. There is an open issue in the tracker to deal with this problem.
There is currently a draft document for potential inclusion in ARIA 1.1. Members of the DIAGRAM working group have been working to prepare an EPUB equivalent that can be presented for consideration during the next EPUB revision so we don't have to wait on the next ARIA revision cycle to be able to include out-of-band descriptions, which is where that attribute comes from. It is documented in the content guidelines, with a big red warning at the top, only as a future-looking option.
Gotcha, thanks Matt.
Chris
Hi Chris, here is an additional pointer with regards to the DIAGRAM project (external image descriptions):
http://diagramcenter.org/development/epubdescribedat.html
Cheers, Dan