Data constraints

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Article #378

#378

From: null
Date: Fri, 06 Nov 1992 15:54

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Newcomer to SGML seeks assitance,

We are trying to define an element which may occur in text as one of a set 
of allowed character strings. That is a kind of PCDATA item constrained to
be a member of a certain set of values.

I would like to be able to write something like :-

<!ELEMENT element - O ("Option1" | "Option2" | "Option3") >

Or use parameter reference entities to replace the text:-

<!ELEMENT element - O ( %option1; | %option2; | %option3;) >

<!ENTITY % option1 "Option1" >
<!ENTITY % option2 "Option2" >
<!ENTITY % option3 "Option3" >

Unfortunately these naive approaches don't work with the SGMLS parser
that we are using and I havn't been able to find the answer in the 
ISO standard.  Any ideas please?

Regards

Steve Hook
s.hook@mcs.surrey.ac.uk

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Message-ID: <1992Nov6.155434.24122@EE.Surrey.Ac.UK>

Path: arc1-ca.pugleaf.net!sparky!uunet!pipex!warwick!uknet!uos-ee!mcs.surrey.ac.uk!(null)

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Path: arc1-ca.pugleaf.net!sparky!uunet!pipex!warwick!uknet!uos-ee!mcs.surrey.ac.uk!(null)
From: @mcs.surrey.ac.uk (null)
Newsgroups: comp.text.sgml
Subject: Data constraints
Message-ID: <1992Nov6.155434.24122@EE.Surrey.Ac.UK>
Date: 6 Nov 92 15:54:34 GMT
Sender: css1sh@mcs.surrey.ac.uk (Stephen Hook)
Followup-To: s.hook@mcs.surrey.ac.uk
Organization: University of Surrey, Guildford, England
Lines: 26