Pete,
I think that the solutions to these problems are probably best found
empirically based on feedback from people who need/prefer accessibility
enhancements to feeds. I was happy to provide some guesses as to what I
thought would work, but I don't have the resources to measure the
effectiveness of any solution. I am hoping that your team at IBM, or another
team with similar resources, will be able to provide some guidance to feed
publishers and tool creators based on usability testing by users with
disabilities.
My guess is that multipart/alternative content would make things *less*
accessible today, not more accessible. My feed reader won't even display
entries that have multipart/alternative content and no tools (I know of)
will help users author entries as multipart/alternate. I also would guess
that users with disabilities would have the most success with (X)HTML
content that uses standard HTML accessibility features to enhance multimedia
that is embedded within it. In other words, Atom content should be marked up
pretty much the same way as a web page.
Accessibility for tasks like editing AtomPub media collections (which are
usually used to store multimedia content that is linked to from other
entries) probably depends mostly on the UI of the client. Whoever builds the
first accessible multimedia-publishing AtomPub client will probably set the
standards for accessibility based on their usability tests.
Regards,
Brian
