Unclear utype prefixing

[jd-au]

Utypes in examples have an “ssa:” prefix, but this is not explained in the normative text of the document.

The statement in §2.11 “UTYPEs are defined within a single name space identifying the data model” is aluding to this requirement, but it could be made clearer by adding a statement to the end of §2.11 ¶2 similar to

All UTYPEs defined in this document should be presented with a namespace of "ssa:"

[jd-au]

I've created a draft erratum at https://wiki.ivoa.net/twiki/bin/view/IVOA/SSA-1_1-Err-5