Part 28 support for Express v2

[David Price]

Ed,

I haven't looked into this in any detail so technically it might not really
make a big difference. I guess I'm speaking from an architecture viewpoint.
If P2x only deals with long forms, then shouldn't the those schemas be
defined in Express 2 rather than P2x? Otherwise, each P2x might do something
different.

If the normative reference is the concern, then P28 E2 can normatively
reference Express 2 but refer to the short-to-long form annex. Then, P28 E2
would only contain text to deal with Express constructs that are in the
output of that transformation. As I said, I haven't been following closely
and so don't have a strong opinion but it sounds like an option.

Cheers,
David

-----Original Message-----
From: Ed Barkmeyer [mailto:edbark at nist.gov] 
Sent: 16 September 2003 14:04
To: David Price
Cc: 'STEP Part 28'; 'SC4 WG11'
Subject: Re: Part 28 support for Express v2


David Price wrote:

> I thought the reason for writing the normative short-to-long in E2 was 
> so that P28, etc. didn't have to change at all.

I understood that the purpose of the mapping was to ensure that we didn't
have to create revision/addendum projects for every 20-series standard, in
order to accommodate EXPRESS v2.  The point Heidi made is that Part 28 v2
already is a "revision project", and since CD1 will appear in November 2003,
it should make a normative reference to ISO 10303-11:2003 and not to ISO
10303-11:1994.

Moreover, as I said in my email, EXPRESS v2 does not seem to require any
special features of Part 28 v2, except for *not mapping* attributes of
generalized data types.  The rest is just a matter of checking that the
wording works.

 > For example, what's the use of
> extensible enums/selects in an XML representation of a long form 
> schema?

None.  In a "long form" exchange schema, the EXTENSIBLE type is no longer 
"extensible" -- whatever it has been extended to in that schema is what is
allowed in the exchange, and nothing more.

-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."