What is the proper mechanic ?
The same mechanic for FT violations.
It happened one other time in the tournament, but the official used the
"running the baseline" signal.
Basially it looks like the running the baseline signal, but pointing to the floor.
How successful could a coach be in trying to correct such a call
Probably about the same probability as it is for any other call.
If you are a betting man and take the possibility of the call being changed, do not bet too much money.
Peace