It isn't like there hasn't always been tech acronyms but they are so causally communicated these days without regard for audience.
And my guess is "average hold time." If you use your brain, you can figure most of them out, unless they are adversarially confusing acronyms.
It's just jargon. Sometimes people forget that their jargon isn't universal.
https://gist.github.com/klaaspieter/12cd68f54bb71a3940eae5cd...