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RE: Is there a way to reuse and extend an enumeration in XML s

• To: "'William J. Kammerer'" <wkammerer@n...>,"XML Developers List" <xml-dev@l...>
• Subject: RE: Is there a way to reuse and extend an enumeration in XML schema
• From: "Sylvia Webb" <swebb@g...>
• Date: Sun, 6 Mar 2005 16:49:10 -0800
• In-reply-to: <0a4201c522ab$03e1d150$c970fea9@CMHNovannet>
• Organization: GEFEG
• Reply-to: <swebb@g...>
• Thread-index: AcUiq5QifzgHVMI2SLiAR6asRAKFEwAAxLEw

Currency codes are just one example.  The more common application of this
use case is with industry or association code lists. There are literally
hundreds of them. These codes are often exchanged between multiple trading
partners within the industry or inter-industry. These codes are not commonly
included in off-the-shelf applications but must be exchanged between trading
partners.

Also keep in mind that the audience for UBL implementers ranges from small
companies that use QuickBooks to large enterprises that have the expertise
and resources to either develop their own applications or modify commercial
applications. Controlling particular codes within the application may not be
an option.

Sylvia Webb
-----Original Message-----
From: William J. Kammerer [mailto:wkammerer@n...] 
Sent: Sunday, March 06, 2005 4:17 PM
To: 'XML Developers List'
Subject: Re:  Is there a way to reuse and extend an enumeration in
XML schema

But in 98% of the cases, folks will make do with the default set of
(standard ISO  4217) currency codes provided for in the "off-the-shelf"
set of UBL schemas. In another 1.9% of the cases, they will want to restrict
the codes to currencies they "understand" or trade in - and would want the
parser to intercept the "unsupported" currencies.
Extending the list is even rarer.

Personally, I think this is spurious logic;  it seems much easier to have
the schema serve only as a general purpose syntax "gate-keeper" - and to
enforce the use of particular currencies (e.g., USD, CAD, GBP and
EUR) within the application.  And if I were intent on allowing the use of a
currency not yet in the "authorized" list, I'd just intercept the parser
exception and check for the one or two unusual codes.

This insistence on "override" code lists must be a hold-over from the days
of EDI.  Nonetheless, it does provide an interesting problem to explore and
to see if the XML schema specification provides an elegant way to do code
list extensibility.

William J. Kammerer
Novannet
Columbus, OH 43221-3859 . USA
+1 (614) 487-0320

----- Original Message -----
From: "Michael Kay" <mike@s...>
To: "'William J. Kammerer'" <wkammerer@n...>; "'XML Developers
List'" <xml-dev@l...>
Sent: Sunday, 06 March, 2005 06:49 PM
Subject: RE:  Is there a way to reuse and extend an enumeration in
XML schema


> I can't speak to Kenneth Stephen's requirements, but I'm pretty sure
> that UBL wants to give users some way of extending (and restricting)
> currency codes (inter alia) without modifying any of the
> distributed UBL schemas.


Surely the right way to tackle this is for the "distributed UBL schemas"
to impose no restrictions on the list of currency codes, and for user
schemas to impose an enumerated list by restricting the "standard" one?

Michael Kay



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    • From: "William J. Kammerer" <wkammerer@n...>

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