I am aware others disagree but I agree. IMO more important to reduce the risk of, for example, mco (presently only applied to questions about Orlando) being applied also to ones about Miscellaneous Charges Orders than it is to be concerned about the exact wording of a Usage guide. The latter may be edited at any time for a 'fix' that applies 'across the board'. Jumbling Orlando with Miscellaneous Charges Orders would require a post by post review to 'unscramble'.
mco is far from unique in the possibility of ambiguity. tsa is presently applied to Transportation Security Administration but, without a Usage guide, for consistency of usage with other IATA codes might just as, or more, easily have been taken to refer to Taipei Songshan Airport.
And there is a swathe of others such as: goa - Presently the Usage guide includes is A small state in India but there is also Genoa Cristoforo Colombo Airport (IATA GOA) and possibilities for ambiguity with
See (!) also Tag sea is used for Seattle-Tacoma International Airport and for Seas (ie big salty waters).
ana is not meant for Angama Mara Airport.
art is not meant for Watertown International Airport.
vfs is not meant for Vision Flight Center though that is its ICAO code.
iata is not meant for the Illinois Art Therapy Association.