Limit number of elements with attribute via XSD?

Question

There is a fragment of XML

    uid-1
    uid-2
    uid-3&         


        

Answer 1

You cannot express your constraint in XSD 1.0, but in XSD 1.1, you can use xs:assert to limit the itemUID elements with key attributes to 0, 2, 3 elements as follows:

Here it is in context in a complete XSD:

XSD 1.1