14 CFR § 221.203 - Unique rule numbers required.
§ 221.203 Unique rule numbers required.
(a) Each “bundled” and “unbundled” normal economy fare applicable to foreign air transportation shall bear a unique rule number.
(b) The unique rule numbers for the fares specified in this section shall be set by mutual agreement between the filer and the Department prior to the implementation of any electronic filing system.