XMI12 — Specification addresses only generation not consumption (medium)

The focus is exclusively on generation of XMI Documents and not on their
consumption: how is the consuming program expected to process/interpret
incoming XMI documents. Some specific questions:

• in what order should the xmi.differences items be applied (compared to
  the rest of the document and with each other);
• how should an incoming document be matched/reconciled with existing
  objects (in a repository) e.g. by uuid, xmi.id, some other nominated
  property? What impact should the version number of the metadata (as opposed
  to the metamodel) have?
• to what extent should the absence of any links for a
  references/composition/association be taken as meaning it should be empty
  (and moreover that any existing links of that type for the object concerned
  should be deleted)
• what if hrefs to another document do not uniquely identify an element
  (e.g. if xmi.label is used)?
  The answers to these questions also have an impact for generators since they
  will need to know the impact of various generation choices and be assured of
  some consistency. If consuming programs can do what they like with the XMI
  file then you lose interoperability.