; or (B) ammunition to be used in firearms. (5) Merchant category code The term merchant category code means a multi-digit code that is issued by the International Organization for Standardization for the purposes of enabling the classification of merchants into specific categories based on the type of business or trade of the merchant or the services supplied by the merchant. (6) Payment card network The term payment card network means an entity that, directly or through a licensed member, processor, or agent, provides a proprietary service, infrastructure, software, or hardware that routes information used to authorize, clear, and settle credit card and debit card transactions. (b) Prohibitions relating to merchant category codes (1) Payment card networks A payment card network may not require a firearms retailer to use, nor require a covered entity to assign to a firearms retailer, a merchant category code that distinguishes the firearms retailer from a general merchandise retailer or a sporting goods retailer. (2) Covered entities Neither a covered entity, nor any agent of a covered entity, may assign to a firearms retailer any merchant category code that distinguishes the firearms retailer from a general merchandise retailer or a sporting goods retailer. (c) Enforcement (1) In general The Attorney General shall— (A) enforce this section, including by conducting investigations of potential violations of this section