2.2.3.2 unsignedByteOrEmpty Simple Type

The unsignedByteOrEmpty simple type represents a value that can either be an xs:unsignedByte type, as specified in [XMLSCHEMA2/2] section 3.3.24, or an empty value.

 <xs:simpleType name="unsignedByteOrEmpty">
   <xs:union memberTypes="xs:unsignedByte EmptyVal"/>
 </xs:simpleType>