Is lack of fallback a feature or a bug?

[rickj]

related to https://github.com/w3c/epub-tests/issues/165 and https://github.com/w3c/epub-tests/issues/245

Should requiring a reading systems to follow the fallback chain to XHTML be required? If the market requirements demand that the source file never be exposed (dare I bring up DRM here?) then requiring XHTML to be exposed is a conflict. This seems like a 'go to market' issue, not a reading system obligation.

[iherman]

Rick, you may be right, but I think issue should be raised on the repository of the spec, not the tests...

[mattgarrish]

If the market requirements demand that the source file never be exposed (dare I bring up DRM here?) then requiring XHTML to be exposed is a conflict.

I'm not sure I follow. What the fallback contains is entirely up to the author, so how would they create their own conflict? It could simply be a page that tells users the intended resource isn't handled by their reading system. Ideally it should be some form of content equivalent so users don't pay for content they then may not be able to access, but that's not required by the spec.