The buying of foreign commercial bills of exchange is the principal medium of bankers and foreign-exchange dealers in placing funds to their credit in banks abroad against which they issue checks, drafts, letters of credit, etc. It is the foundation of most of our foreign-exchange transactions. It is the principal source of profit in the business. It enables manufacturers to sell their goods abroad for cash in advance.

Foreign bills of exchange vary as to conditions of payments abroad. If conditions of sale between buyer and seller of the goods were that goods were to be paid for upon delivery, the instructions accompanying the bill would say "documents for payment" (expressed d.p.), meaning not to deliver the bill of lading (which would enable drawee to get goods) until draft had been paid.

If instructions said "documents for acceptance" (expressed d. a.), it would mean that bill of lading could be delivered when draft was accepted, thus enabling drawee to obtain goods at once and pay draft any time within sixty-three days (if a sixty-day bill).