The reading system spec has this high-level requirement for the package document:

[A Reading System] MUST honor all presentation logic expressed through the Package Document [EPUB-33] (e.g., the reading order, fallback chains, page progression direction and fixed layouts).

https://w3c.github.io/epub-specs/epub33/rs/#sec-package-rs-conformance

The inclusion of fixed layouts in the examples is confusing, though, as it there is a separate bullet for fixed layout handling in the same list.

I believe the intention of this bullet was only to require support for the "presentation logic" expressed directly through the elements and attributes of the package document, not indirectly through metadata expressed in meta tags.

On top of the general ambiguity about what "presentation logic" refers to, "honor" isn't exactly a technical term. The bullet seems more like an indirection to actual requirements/recommendations than something that can be tested.

In any case, it needs work.