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Re: optional, but at least one required

From: George Cristian Bina <george@oxygenxml.com>
Date: Wed, 10 Oct 2007 10:42:23 +0300
Message-ID: <470C825F.3080003@oxygenxml.com>
To: vwiswell@verizon.net
Cc: xmlschema-dev@w3.org

Hi Virginia,

I understand that what you want is
ab* | a*b
and you need to write that in a non ambiguous way to be able to write it 
in XML Schema.

So what we need to accept is

a ab abb abbb ...
b ab aab aaab ...

You can write that as

((a, (b* | (a+, b))) | b)

Best Regards,
George Cristian Bina - http://aboutxml.blogspot.com/
<oXygen/> XML Editor, Schema Editor and XSLT Editor/Debugger

Virginia Wiswell wrote:
> I have a similar situation that I'm having trouble with. I have a and b, at
> least one of them has to appear once AND ONLY ONCE. a must come before b.
> The examples in this thread allow more than one occurrence of a or b.
> This is my first attempt at customizing a schema and I'm stuck.
> TIA, Virginia
>> You need to specify the requirements in a little more detail:
>> * are multiple occurrences of a, b, and c allowed?
>> * what constraints do you want to impose on the ordering of the elements?
>> Michael Kay
>> http://www.saxonica.com/
Received on Wednesday, 10 October 2007 07:44:44 UTC

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