DSF2 Definition of Throwback Table (dph.hst)
The throwback table is built by taking the address instruction code of “T”
which is a PO Box Throwback record from the delivery file.
The address sort instruction code provides optional information that can be
used by automated equipment (MLOCR and BCS machines), to allow
special handling (either manual or automated) of specific delivery addresses.
“T” = PO Box delivery – the address associated with this delivery point is a
street address, but delivery is made to the customer’s post office box