@lermontov
AN/DP just requires AOW. Oddly, Helitrox requires AOW with deep speciality (or Intro to Tech or equivalent).
TDI Helitrox Diver - SDI | TDI | ERDI | PFI
Could be that ANDP+Helitrox is 45m rated (or was when I did it) whereas ANDP is just 40m.
The main thing they're looking for is the core skills to do the switches, shutdowns, stage cylinder switches, holding stops, etc.