if you are asking what the roughin height for the drain and water,
most double's use 1 drain and a continuous waste.
you need what is called a "cut sheet" ask your foremen/stupidintendent for the cutsheet
its the rough in measurements for the unit hanger, water, drain, electricity.
all measurements come off the center of the drain.
so, if your cut sheets says the drain roughs in at 10" and the drain in the field is at 11"
then pull all your measurments off the drain. cause it is not going to move.
this is something most electricians can not seem to grasp. and there rough in winds up off. lol