force uniqueness in xml schema

[Robert Ludewig]

<LinkList>
<Link ID="A01" />
<Link ID="A02" />
<Link ID="A03" />
<Link ID="A01" />
</LinkList>

How can I specify in a xmlschema that in the linklist are no occurences with
same ID ?
(Last Link is illegal)

 

[Martin Honnen]

<LinkList>
<Link ID="A01" />
<Link ID="A02" />
<Link ID="A03" />
<Link ID="A01" />
</LinkList>

How can I specify in a xmlschema that in the linklist are no occurences with
same ID ?
(Last Link is illegal)

Use the type xs:ID for the attribute named ID.