Field help (REP) 

The sales reps are initialized by the customer sales reps, then by those of the ship-to customer, if no sales rep exists in the customer record. In the case of a prospect, the representatives of the prospect are not considered. These sales rep codes are copied to the document lines. If a representative is modified in the document header upon creation or when lines exist in the document, the system suggests to copy the modification to all the lines that already exist.