So that sounds like an integration scenario - I didn’t think Ian or Heather were talking primarily about this (end of life and other such use cases - data would be provided by application).
Which is the attraction of the ‘cheap’ version - it’s just a special EHR in the CDR, containing normal Compositions and Entries, so the only extra functionality that is needed is to create (some) demographic objects in that special EHR (call it D) rather than in the EHR being worked on (for some patient P), and connect the demographic refs in P’s EHR to those in the D EHR. Plus a bit of additional work to enable applications to search on existing demographic items within the D record, which gets you reuse.
That is of course true. But why would the cache be deleted or become outdated?
Well in fact… it is!
Also, tools like Archetype Designer get their model definition from BMM files, and those include the whole demographic model. So making archetypes of demographic entities is possible today in that tool.
Plus, this proposal adds some missing representational power to the demographic model.