"2 Conformance" says:
    An IDL fragment is considered to be a conforming IDL fragment if
    it satisfies all of the MUST-, REQUIRED- and SHALL-level criteria
    in this specification that apply to IDL fragments.

However, consider a requirement such as:
    Within the set of IDL fragments that a given implementation supports,
    the identifier of every <foo> MUST NOT be the same as the identifier
    of any other <foo>.

This requirement operates on a *set* of IDL fragments, so (when you have multiple fragments) it doesn't really make sense to ask if individual fragments satisfy it. 

So perhaps the conformance section should instead be based on a definition of a conforming *set* of IDL fragments.