• From: "James Tauber" <jtauber@j...>
• To: <xml-dev@i...>
• Date: Sat, 28 Nov 1998 13:30:27 +0800

-----Original Message-----
From: roddey@u... <roddey@u...>


>How can you represent a strictly acyclic graph using ID/IDREF? For
>instance, if you have an employee list, and every employee has an ID
>attribute which is his/her employee number and an IDREF attribute which
>refers to his/her manager, what do you do when you reach Le Gran Fromage
>(sp?)? This person has no manager, but the parser will consider it an error
>if his/her manager field does not refer to someone else's employee id.

You could just make the IDREF attribute #IMPLIED:

<!ATTLIST employee
    id    ID    #REQUIRED
    manager    IDREF    #IMPLIED
>

James
--
James Tauber / jtauber@j... / www.jtauber.com
Associate Researcher, Electronic Commerce Network
Curtin University of Technology, Perth, Western Australia

Maintainer of : www.xmlinfo.com,  www.xmlsoftware.com and www.schema.net



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