If you have the specific Pack ID from the Epicor ERP you will enter one of the following depending on the type of shipment.
XXXX is the actual Pack ID number:
CSXXXX = Customer Shipment Pack
MPXXXX = Master Pack
MSXXXX = Miscellaneous Shipment Pack
SCXXXX = Subcontractor Shipment Pack
If you are looking at the Reference field or using the Reference field for your search options, the above information is used without the leading 'P'.