To the point: can you point me to where it is stated that validity to the manifest schema is a ODF conformance requirement? No, I don't think you can, because such a requirement does not exist.
Rob Weir - IBM / Chief ODF Architect
Brilliant and simple answer
... I regard the schema as an equivalent case. It is a *grammar* which formally makes unambiguous formal provisions about the disposition of XML elements and attributes declared in a certain namespace. If the schema mandates that element x MUST contain element y, and an XML manifest makes use of element x but fails to use element y as mandated, then I say that document is as surely non-conformant as the one which disregards the ZIP format provisions mentioned above.
Alex Brown - Griffin Brown Digital Publishing Ltd / Technical Director