 Messaging standards, such as the AHM 780 Aircraft Movement Message specification, specify that only the numeric codes should be used.Many airlines further subdivide the IATA codes with an additional character, for more granular delay analysis, but these are not standardized.In the AHM 780 specification, the two-character numeric-only codes are sent in the "DL" and "EDL" elements along with the time assigned to each code (e.g.