Unused selects in SHTOLO

[Ed Barkmeyer]

Rob is correct that the process of extending EXTENSIBLE SELECT types produces 
artifact select types that have no use.  This may or may not also apply to 
EXTENSIBLE ENUMERATION types.

I have no objection to the rule Rob intends, but I think we may want to be a bit 
careful about the wording:

(1) The rule should include both SELECT types and ENUMERATION types, and could 
in general apply to any data type that is created by a TYPE declaration and has 
no "role" (is not the data type of any attribute) in the resulting schema.  Any 
such data type need not be included in the long form schema, but:

(2) When a SELECT data type plays a role, every (interfaced) data type in the 
select list of that select type also plays that role.

(3) When a defined data type is included in the long-form schema, its 
underlying-type must be included in the schema, even if it plays no role.

-Ed

-- 
Edward J. Barkmeyer                       Email: edbark at nist.gov
National Institute of Standards & Technology
Manufacturing Systems Integration Division
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