2.2.5.5 guid (from namespace http://schemas.microsoft.com/2003/10/Serialization/)

Reserved. MUST be ignored.

 <xs:simpleType name="guid">
   <xs:restriction base="xs:string">
     <xs:pattern value="[\da-fA-F]{8}-[\da-fA-F]{4}-[\da-fA-F]{4}-[\da-fA-F]{4}-[\da-fA-F]{12}"/>
   </xs:restriction>
 </xs:simpleType>