This map provides a solution to the problem described here: http://twhl.info/journals.php?id=8465
Three doors; A, B, and C are set to be usable, and togglable.
Door C can only be used if Door A is open and door B is closed.
Doors A and B can only be used if Door C is closed.
By default, when the map loads, all outputs are off.
There is a trigger_auto that triggers a multisource that toggles the output states of relays.
Door A targets Door_C_Master
Door B targets Door_B_Inverter
Door_B_Inverter targets Door_C_Master
When door b is open(on), door b inverter forwards an "off" signal
Door C targets Door_C_inverter
Door_C_Inverter targets A_B_Master
When door c is open(on), door c inverter forwards an "off" signal
When door c is on, the A&B master is DISABLED so doors a and b cannot be used
when door A is open and B is closed, both signals going to the master are "on" (because the b signal is inverted)
In all other combinations of doors A and B, Door_C_Master is disabled, preventing it from opening.