It appears in our rewrite of URL processing that we've lost the requirement for there to be a resource at the end of relative paths. In 3.2, we had this statement:

All relative IRI references MUST resolve to resources within the OCF Abstract Container (i.e., at or below the Root Directory).

This was meant to cover both that the URL not leak outside the container and that there must be a resource at the end of it.

Our new rewrite covers URLs not leaking outside the container better, but we no longer appear to have a requirement that there be a resource at the destination. Without that bit, someone could argue that missing resources in the container aren't really errors.

We should add back a statement about the need for a resource to be present so that we're consistent again with previous versions of EPUB 3.