xml schema: set only a particular value as unique

[korkless]

hi, i have a xml as

<itemCollection >
<item enabled="false" />
<item enabled="true" />
<item enabled="false" />
</itemCollection>

I want know if exists a solution with xml schema for validate that only one child can have enabled='true' .
If no way exists somebody have a solution for reformat my xml and do what i want?
thanks

[jkmyoung]

This isn't possible with just xml schema.

You'd need to use something like schematron, or a different schema extension/alternative for this type of rule.