EXPRESS Ed.2 SEDS

[Wilson, Peter R]

Ed,

    It's fortunate that the wording is in a Note, isn't it?

    I think that there is a problem in that the "wordy meaning" of ONEOF depends on the context. What about:
             ONEOF(a,b) AND ONEOF(c,d)
In this case your proposed wording change won't convey the right impression (there must be one from (a,b) and one from (c,d), whereas the rewording implies that there need not be any of a,b,c,d).

    Let's leave it as it is.

Peter W.

Dr Peter R. Wilson
Boeing Commercial Airplanes
PO Box 3707, MS 2R-97, Seattle, WA 98124-2207
Tel: (206) 544-0589, Fax: (206) 544-5889
Email: peter.r.wilson at boeing.com
--------------------------------
Any opinions expressed above are personal;
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> -----Original Message-----
> From: Ed Barkmeyer [mailto:edbark at nist.gov] 
> Sent: Thursday, January 08, 2004 11:33 AM
> To: SC4 WG11
> Subject: EXPRESS Ed.2 SEDS
> 
> 
> All,
> 
> Tom Kramer and Peter Denno brought the following to my attention:
> 
> Problem Statement:
> 
> In Part 11.2:2003, clause 9.2.5.2, after the normative text, 
> the following NOTE 
> is to be found:
> 
> "NOTE The phrase ONEOF(a,b,c) reads in natural language as 
> 'an instance shall 
> consist of one and only one of the entity data types a,b,c.'"
> 
> The NOTE does not correctly convey the intent of the normative text.
> 
> Proposed change:
> 
> Either: The words "one and only one" should be replaced by 
> "at most one"
> or: the words "shall consist of one and only one" should be 
> replaced by "shall not consist of more than one".  (I prefer 
> the latter.)
> 
> Discussion:
> 
> The NOTE is incorrect in that it causes the following 
> mis-interpretation:
> 
> ENTITY xyz; ... END_ENTITY;
> ENTITY a SUBTYPE OF (xyz); ... END_ENTITY;
> ENTITY b SUBTYPE OF (xyz); ... END_ENTITY;
> ENTITY c SUBTYPE OF (xyz); ... END_ENTITY;
> ENTITY q SUBTYPE OF (xyz); ... END_ENTITY;
> SUBTYPE_CONSTRAINT XYZ_not_both_A_B FOR (xyz);
>   sc1: ONEOF(a,b,c);
> END_SUBTYPE_CONSTRAINT;
> 
> Consider the instance (external mapping):
>   #123 = (D(...) Q(...));
> 
> #123 is a valid instance of d and q according to the 
> normative text, but it is an invalid instance according to 
> the NOTE, since it does not consist 
> of any of the data types a,b,c.
> 
> -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: +1 301-975-4694
> 
> "The opinions expressed above do not reflect consensus of 
> NIST, and have not been reviewed by any Government authority."
> 
>