There is a fragment of XML
uid-1
uid-2
uid-3&
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:
<xs:assert test="count(itemUID[@key]) = (0, 2, 3)"/>
Here it is in context in a complete XSD:
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema attributeFormDefault="unqualified"
elementFormDefault="qualified"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:vc="http://www.w3.org/2007/XMLSchema-versioning"
vc:minVersion="1.1">
<xs:element name="items">
<xs:complexType>
<xs:sequence>
<xs:element name="itemUID" minOccurs="1" maxOccurs="unbounded">
<xs:complexType>
<xs:simpleContent>
<xs:extension base="xs:string">
<xs:attribute name="key" type="xs:boolean">
</xs:attribute>
</xs:extension>
</xs:simpleContent>
</xs:complexType>
</xs:element>
</xs:sequence>
<xs:assert test="count(itemUID[@key]) = (0, 2, 3)"/>
</xs:complexType>
</xs:element>
</xs:schema>