I do not have a really strong opinion but multiple times when seeing these questions, I wanted to close them as off-topic, and then I saw that we had a lot of questions on the topic, so I didn't close but wondered.
These Amadeus/Sabre/... acronyms/commands have an actual meaning in terms of travelling. Usually, it is not the traveller's duty to know them, though, only the travel agent. I think that it can easily be on-topic for most cases:
- It describes part or all of your itinerary
- It describes your fare, and gives important information on your ticket conditions
- We have a lot of other questions on deciphering tickets, or even anything, so that makes sense to keep these on-topic for the sake of curiosity (tagged with factoids or gds, for example)
That's for the ticket part, once it is issued.
For the booking, it might help you in very specific cases (e.g. to check your booking is correct, the same way you'd make sure the travel agent spells your name right), but normally it is the travel agent's job. On that point, I have a funny anecdote of a friend working at Amadeus and booking a ticket in China with a travel agent, they ended up communicating more through the Amadeus "language" than in English. That does not make it on-topic, because these booking commands require deep knowledge (there are literally dictionaries of commands).
So my opinion is basically the same as @MeNoTalk. And I would tend, in case of doubt, to keep the question open. We have a lot of more random curiosity questions, and there are apparently people able to satisfy the curiosity of others on that topic.