W3C home > Mailing lists > Public > xmlschema-dev@w3.org > October 2012

Re: Order indicators in the .xsd file

From: C. M. Sperberg-McQueen <cmsmcq@blackmesatech.com>
Date: Wed, 17 Oct 2012 20:51:36 -0600
Cc: "C. M. Sperberg-McQueen" <cmsmcq@blackmesatech.com>, "G. Ken Holman" <gkholman@CraneSoftwrights.com>, xmlschema-dev@w3.org
Message-Id: <D3B5755E-C60A-4E25-838D-364A2F5DE93D@blackmesatech.com>
To: George Cristian Bina <george@oxygenxml.com>

On Oct 17, 2012, at 8:39 AM, George Cristian Bina wrote:

> Expression every possible permutation does not generally work as you will get a lot of errors from the unique particle attribution rule that will not allow you to say for example
> 	(a, b, x) | (a, b, y)
> forcing you to write
> 	(a, b, (x | y))
> instead.
> 
> However, for a complex model getting the right expression is not easy and sometimes it may be impossible.

I agree that it is often difficult, and the result is almost never
easy to read and understand.  But I do not believe it is ever 
impossible.  

There is a definable class of regular languages for 
which deterministic content models are impossible, and the
problem of interleaving a number of elements with different
occurrence constraints does not look at first glance as if it had
the required properties.  (But I have not attempted a formal
proof of this proposition and I may be wrong.)

-- 
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* C. M. Sperberg-McQueen, Black Mesa Technologies LLC
* http://www.blackmesatech.com 
* http://cmsmcq.com/mib                 
* http://balisage.net
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Received on Thursday, 18 October 2012 02:52:02 UTC

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