How to exclude a certain purchase order type from On-Receipt total

The Purchase Order Entry program P4311 Item Availability processing option allows you to enter a '1' to update the "Quantity on Other PO's" field (OT1A) in the Item Branch or Location files (i.e. Requisitions and Blanket orders).  If left blank, the "Quantity on PO" field (PREQ) will be updated.  When populated with a 1 the system will update the Quantity on Other PO's field (OT1A in F41021).  When this processing option is left blank the Quantity on PO field (PREQ) will be updated.