Biot of a thread drift but many of these 'codes' go back to the days of morse or '5 unit code telegraphy' (the ones with the punched paper tape you see in old films with telex machines and teleprinters.
The Aviation world had its Q codes as described but many other industries had codes for their own use-in the telecoms world there was a series of 'five letter codes; which covered a wide range of every day phrases all designed to save 'words' in the pay by the word teelgraph world and the make the transmission quicker military world.
In the early days of my career I sent many telegrams with just the code word TUNHO on them which meant -'your message is acknowledged and we will respond shortly ; and there were hundreds of them covering everyday business situation. the finance industry had its own codes and the telegraph world had its widely used 'commercial code' that consisted of pronounceable in non existent words of varying length which were considered acceptable for customers to sue when sendign messages to save on the per word charges
of course all these things rendered 90% of telegrams illegible to anyone not in the same industry and no doubt the 'old sweats' of the aviation world could read back a message full of codes for locations and QSYs and QNHs without a pause. In my industry we had guys who could read a teleprinter tape as though it was the written word going from the punch hole code to the code word to the meanign of the code word in one smooth step.
i often wonder how long and at what cost the ICAO and NATO phonetic alphabet to be developed from the more homely Able Baker Charlie of the wartime RAF.
I suppose if facebook get their way and a 21st century 'inclusive ' version is promoted it really is a solution to a problem that doesn't exist since so many people world wide know the current ICAO /NATO version