1. The user guidelines, indicating that the date encoding of "marc"
applies only to <dateIssued>, are inconsistent with the schema, which
allows encoding="marc" on any date element.
2. 'lang' and 'script' attributes should each have enumerated type.
3. This may be intentional, but why are the authority attributes on
<placeTerm> and <geographicCode> the only ones with a restricted
vocabulary coded in the schema? Other authority attributes with a fixed
set of possible values are of type xsd:string, with only schema
documentation directing the user to the vocabulary.