schema: different occurence types

[Th.-Fischer]

hi,
i have this xml structure
<users>
<user id="root"/> <!-- mandatory! -->
<user id="a"/> <!-- optional -->
<user id="b"/> <!-- optional -->
<user id="c"/> <!-- optional -->
</users>

what i like to define in schema is, that users
MUST HAVE 1 user element with id="root" and
CAN HAVE any other user elements.

My (not working) attempt (userRootType is derived
from userType with restriction pattern="root" for id):

<xsd:element name="users">
<xsd:complexType>
<xsd:sequence>
<xsd:element name="user" type="fcms:userRootType"/>
<xsd:element name="user" type="fcms:userType"
minOccurs="0" maxOccurs="unbounded"
/>
</xsd:sequence>
</xsd:complexType>
</xsd:element>

Is it possible, or need I different named elements?
Any Ideas?

 

[Stan Kitsis [MSFT]]

You cannot do this with XML Schema. Your best bet is something like:

<users>
<rootUser /> <!-- mandatory! -->
<user id="a"/> <!-- optional -->
<user id="b"/> <!-- optional -->
<user id="c"/> <!-- optional -->
</users>

--
Stan Kitsis
Program Manager, XML Technologies
Microsoft Corporation

This posting is provided "AS IS" with no warranties, and confers no rights.
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[Henry S. Thompson]

Sure -- add a 'fixed' attribute called 'root' with value 'root' to the
<users> element, then define a <key>, which establishes id as a key
for user under users, and define a <keyref>, which identifies
root/@root as a reference to the 'id' key.

See the Identity Constraint chapter of the W3C XML Schema Primer [1] for
help with this.

ht

[1] http://www.w3.org/TR/xmlschema-0/#specifyingKeysAndtheirRefs
--
Henry S. Thompson, HCRC Language Technology Group, University of Edinburgh
Half-time member of W3C Team
2 Buccleuch Place, Edinburgh EH8 9LW, SCOTLAND -- (44) 131 650-4440
Fax: (44) 131 650-4587, e-mail: (e-mail address removed)
URL: http://www.ltg.ed.ac.uk/~ht/
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