<xs:simpleType name="dateString" xmlns:xs="http://www.w3.org/2001/XMLSchema"> <xs:restriction base="pc:defaultString"> <xs:minLength value="10" /> <xs:maxLength value="10" /> <xs:pattern value="[0-9]{4}-[0-9]{2}-[0-9]{2}" /> </xs:restriction> </xs:simpleType>