What is the difference between Usance LC and DA?

Usance LC is a letter of credit payable at a predetermined time after the presentation of conforming documents. These are also called time L/C or deferred payment L/C and are the opposite of L/Cs payable at sight.

Whereas "DA" or As I assume D/A "Documents Against acceptance" is an arrangement in which an exporter instructs a bank to hand over shipping and title documents to an importer only if the importer accepts the accompanying bill of exchange or draft by signing it.

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