SEDS for ISO 10303-11: TYPEOF(x:NUMBER)

[Ed Barkmeyer]

All,

I think there is merit in Jochen's SEDS.  Because of the wording in question -- 
"- if the current name is the name of a simple data type: skip;" --
the later requirement for the result set to include "specializations or subtypes actually instantiated in the value" is not
applied to "primitive" types.  But primitive types *can* have specializations -- Part 11 specifies that BOOLEAN is a
specialization of LOGICAL and REAL is a specialization of NUMBER.  

I agree with Jochen that it is proper to require TYPEOF to return every type of which the actual parameter value is specified by
Part 11 to be an instance.  (It should be noted that the wording of 15.25 can cause the result set to include types with which
the actual parameter value is specified by Part 11 only to be compatible.  Surely it should return all types of which the value
is actually an instance!)

I suspect that the decision to make BOOLEAN and REAL "specializations" may well have *followed* the last repair of TYPEOF in the
IS, and we didn't do a very good job of the kind of engineering change management that STEP is designed to support.  I.e. this
is one of those cases in which the revision to clause 8 didn't quite fit the form, fit and function requirements of the uses of
it in clause 15!  ;-)  But there may have been a reason for specifically excluding this case. I know for a fact that the Spiby,
Sanderson, Wilson, Wenzel concepts of the EXPRESS product don't quite match mine!  So I would prefer to hear from those to whom
the text of the specification has long been entrusted.

-Ed

-- 
Edward J. Barkmeyer                       Email: edbark at nist.gov
National Institute of Standards & Technology
Manufacturing Systems Integration Division
100 Bureau Drive, Mail Stop 8260          Tel: +1 301-975-3528
Gaithersburg, MD 20899-8260               FAX: +1 301-975-4482

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