Spooky 2:
Each operator, depending on equipment, decides on a procedure that is factory approved along with regulatory approvals. They do not simply make this stuff up on their own. The 200' AH is simply a point of reference and is almost always lowered to something below 100' and 50' is most common these days.
Which is why neither DA or AH are charted on CAT III approach charts, at least not in the U.S.