Operating regulations is the traditional name for card network rules, the binding rulebooks that a card network issues to the financial institutions and processors that take part in its system. The main entry describes what these rules cover and how they are enforced. Despite the word regulations, they are private contractual rules written by the network, not laws or rules made by a government regulator.
The phrase comes chiefly from Visa, whose rulebook was long titled the Visa International Operating Regulations before being reorganised as the Visa Core Rules and Visa Product and Service Rules. Mastercard publishes the Mastercard Rules together with separate manuals on subjects such as chargebacks and security. The older term remains common in merchant agreements, which typically oblige the merchant to comply with the operating regulations of each card brand it accepts, and in court cases and regulatory orders.
The term is used for other payment systems as well. The rulebook of the United States ACH Network is formally the Nacha Operating Rules, covered under Nacha Rules, and the general concept for any payment scheme is discussed under scheme rules. Following the rules in practice is the subject of card scheme compliance.