Have a good look at the trip relay banks in question. A "no coil" switch stack is usually activated by an arm attached to some of its neighboring switch stacks in the relay bank. An example might have a trip relay for the A, B and C targets and a "no coil" set of switches mounted between A and B (or B and C) trip relays that only trips once the other three have all tripped. It's a mechanical AND gate.
/Mark