If the floor waste required next to a shower area is fitted, the finished floor falls to that waste at 1:100 or steeper. Notes recommend that surface water drains to the waste, does not leave the room at the threshold in normal use, and that the whole Category 2 floor is graded where it drains to the shower waste.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.