No normative values for xsd:string

There are 40 instances where attributes have the value of xsd:string. I have only checked a sampling of them but the ones I checked all suffer from the same problem as at, by, and choice, i.e., no defined semantics. It isn't possible to have conformance clauses in the absence of defined semantics. What would it mean to conform to "?" How would we achieve interchange, one of the purposes of normative requirements, perhaps the most important one.

If the thought is to pass the declaration of normative values for xsd:string to a profile, then part 1 should be written with conformance clauses for profiles which then define these values.