Let me see if I can make this more tangible with a real world messaging
community.   In public safety, there is the concept of an incident.  Seems
well-bounded?  Is it?

How many community types are there?  Just to start:

O Advisory
O Aviation
O Fire
O Police
O EMA
O EMS
O Geophysical
O Hazmat
O Health
O Infrastructure
O Meteorological
O Security
O Structural
O Terrorism
O Transportation

Do they all share a single vocabulary for incidents?  Do they share an
incident class with subtypes?  Do they use different incidents which are
subtypes in name only?  Do they use a message type with generic boxes for
information which human analysts sift with automated tools and out of which
they sift it into just a few reports or a dashboard?

HINT:  The answer is yes to all of the above.  It varies by procurement.

By the way, sometimes they say 'event' for 'incident' and sometimes they say
'incident' for 'event'.  The difference is not content but the way time is
used as a qualifier.  What should one abstract away to make that converge?

len                                                                  
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