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RE: xs:choice and xs:sequence question

From: Michael Kay <mike@saxonica.com>
Date: Thu, 12 Jan 2006 17:04:02 -0000
To: "'George Cristian Bina'" <george@oxygenxml.com>, <d_a_carver@yahoo.com>
Cc: <xmlschema-dev@w3.org>
Message-ID: <E1Ex5sP-0002kM-KQ@lisa.w3.org>

> oXygen reports the error with a link to the specification 
> related with that:
> http://www.w3.org/TR/xmlschema-1/#cos-nonambig

A tangential remark: I wonder how useful this is? I know Appendix C says
that validity errors "should" be reported citing the chapter and verse of
the spec, but is there really any serious prospect that the average schema
author will get any value from this? Your link points to the sentence:

"A content model must be formed such that during .validation. of an element
information item sequence, the particle component contained directly,
indirectly or .implicitly. therein with which to attempt to .validate. each
item in the sequence in turn can be uniquely determined without examining
the content or attributes of that item, and without any information about
the items in the remainder of the sequence."

I suspect most users can't even parse the syntax of this sentence, let alone
understand what it means.

I decided in Saxon that there wasn't any point in referring people to the
spec, and instead try to explain what's wrong in my own words. In this case
you will get a message to the effect: "the content model is ambiguous,
<elementname> appears in more than one place".

Any views on this from users?

Michael Kay
http://www.saxonica.com/
Received on Thursday, 12 January 2006 17:04:51 GMT

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