Pilots often use non-standard-phraseology for readbacks. Some examples:
ATC: DLM, switch to tower, 121.2
P: tower, for DLM
ATC: DLM, identified, climb via the RIDA9 departure
P: roger, climb via, DLM
DLM, cleared for takeoff runway 17
P: cleared for takeoff, DLM
The last two example are from two videos by Boldmethod, How To Fly An IFR Departure Procedure With A "Climb Via" and How To Fly An Instrument Arrival Procedure (STAR), used by an ExpressJet-pilot.
Especially the two last ones were a bit shocking to me when I heard a professional pilot using them. So I now want to ask, how far is this "ATC-Slang" allowed to go?