The following text shows an element Size that is a union of two simple types, size_no and size_string:

<xs:element name="Size">
  <xs:simpleType>
    <xs:union memberTypes="size_no size_string" />
  </xs:simpleType>
</xs:element>
 

To map the size to an output port, create one port for the size. Configure the output port as a string. You can configure another transformation in the mapping to convert the data to another type.