Data Types R3 issues

This is the register of known data types issues for release 3.

For now, just enter the change proposal as a single point in the list, with your name

• Collapse Abstract and ISO 21090 into a single specification partitioned according to SAIF (Grahame)
• Turn II.scope into a mandatory attribute Rene spronk
  • In MnM we discussed this and there are issues about making something mandatory that may be populated unsafely (Lloyd).
  • In general anything mandatory is a nuisance for implementers and may be populated quickly, dirty and/or unsafely. As such Loyds argument applies to all mandatory model elements. Given the importance of II.scope to determine object equivalence there are IMHO sufficient reasons to consider turning this into a mandatory attribute. It's a tradeoff between the chances of unsafe use, and having to deal with a heap of implementation issues that we're facing without II.scope being present. (Rene)
• Add 'conformance' into datatype properties (Lloyd)
  • introducing idea of "conformance" (required, optional, not permitted) into the datatype properties. E.g. "You are conformant if you ignore displayName, but not if you ignore code"
• Introduce idea of "implementation" or "closed community" constraints on datatypes (Lloyd) (but initiated by Grahame)
  • implementers to be able to do things like constrain out the root when it's known. I.e. "non-worst case interoperability".