<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE ShipmentsRelation 
[<!ELEMENT ShipmentsRelation (ShipmentTuple*)>
<!ELEMENT ShipmentTuple (QTY)>
<!ATTLIST ShipmentTuple SNUM  IDREF #REQUIRED>
<!ATTLIST ShipmentTuple PNUM  IDREF #REQUIRED>
]>
<ShipmentsRelation>
  <ShipmentTuple>
    <SNUM>S1</SNUM>
    <PNUM>P1</PNUM>
    <QTY>100</QTY>
  </ShipmentTuple>

  <ShipmentTuple>
    <SNUM>S1</SNUM>
    <PNUM>P2</PNUM>
    <QTY>200</QTY>
  </ShipmentTuple>

</ShipmentsRelation>

