Media overlays in accessMode declarations #2303
Description
As I mentioned in a mailing list comment:
EPUB’s media overlays feature means you could have a sufficient auditory pathway. Media overlays are not how the information is encoded or required to be played by default, so I wouldn’t expect the publisher to list auditory as an access mode based solely on their presence. But they do provide you an auditory playback option provided the complete text is narrated (i.e., they’re more like an affordance).
Full text books with media overlays are not audiobooks as we know them, so saying there is an audio requirement is misleading to me. I would only list auditory as an accessMode when you have to turn on media overlays to get the full information of the book (i.e., when they're more like DAISY audio books with minimal text for chapter navigation).
Whatever we ultimately resolve here should also be noted in the techniques (and other places like the DAISY KB).