The Green Drywall was made in Edmonton a tag said somewhere but I could not find out any brand name at all. It's brown in colour - I've not seen this before but I don't work with drywall when building showers and never bought into the "Moisture Resistant" concept.
Look at the colour of this stuff.
They kept the board off the tub lip about an 1/8" and that's it.
One clip and the rest was wafer head screws holding the steel tub still.