14 CFR 221.200 - Content and explanation of abbreviations, reference marks and symbols.
(a) Content. The format to be used for any electronic tariff must be that agreed to in advance as provided for in § 221.180, and must include those data elements set forth in § 221.202. Those portions that are filed in paper form shall comply in all respects with part 221, subparts A through Q.
(b) Explanation of abbreviations, reference marks and symbols. Abbreviations, reference marks and symbols which are used in the tariff shall be explained in each tariff.
(1) The following symbols shall be used:
(2) Other symbols may be used only when an explanation is provided in each tariff and such symbols are consistent throughout all the electronically filed tariffs from that time forward.