The following pattern limits the number of leading zeros to up to 2: <?xml version="1.0"?> <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:simpleType name="myByte"> <xs:restriction base="xs:byte"> <xs:pattern value="0{0,2}1?5?"/> </xs:restriction> </xs:simpleType> </xs:schema>