I wired all limit switches and verified behavior of every limit switch and every estop button.
Now both estop buttons work. Also all five limit switches work.
I have also discovered something nice: the mill actually has separate home switches on all axis.
However, the schematic that I have, has no reference to those, it may be an extra option on my mill that is not reflected in standard schematic.
I understand that with homing switches, my mill could very rapidly home itself in all three dimensions at once. Which is a plus. At the same time, it is not an absolute necessity.i