ISO 18245:2003

ISO 18245:2003 defines code values used to enable the classification of merchants into specific categories based on the type of business, trade or services supplied. Values are specified only for those merchant categories that are generally expected to originate retail financial transactions.
ISO 18245:2003 also establishes the procedures for a Registration and Maintenance Management Group (RMMG), which considers requests for new code values, and a Maintenance Agency (MA), which provides the administrative procedures required to maintain an up-to-date list of codes.
It is not within the scope of ISO 18245:2003 to mandate the use of merchant category codes in any given situation.