The member institution (or member service provider) that maintains merchant relationships, acquires data (itself or through its agent) relevant to a card transaction from a merchant or card acceptor, and submits that data into a payment system.
Acceptance stands for the process of accepting a particular brand of card by a merchant or unmanned terminal.
The process by which a transaction request is approved or declined. In general, the decision to approve or decline a transaction is taken by the issuer, or by a third-party acting on behalf of the issuer. In relation to chip cards, the approval may be given by the chip, within limits specified by the issuer.