Well, maybe I’m overthinking it. I understand that for a fair amount of users it’s a convention, but I really don’t see the logic in the actual choice of letters. Sure, “D” for “Dialog”, but there’s nothing in “X” that indicates that it means “stem”. There’s no “x” in “stem” or “dialog”.
Curiously, in the only US delivery specifications I’ve seen where they actually demand a specific spelling of the rendered channels I’ve seen the following:
MU (music)
MnE (Music & Effects)
OCD (On-Camera-Dialog)
FXST (Effects Stereo)
NAR (Narration)
And when I don’t get told what to do I typically deliver something like “[project/mix name] - Dialog Stem”
I just find the “X” odd, and I’ve come to the conclusion that just spelling the whole thing out makes it virtually impossible to misunderstand what it is, and part of it is that I find the “abbreviations” are more understandable between us engineers, and much less so for other people. And unfortunately we’re dealing more and more with video editors etc that use our stems (and mixes).
Anyway, just curious…