Re: C&S signal

Single boards like this "Swift" type governed BOTH directions on a single track.

Normally if the train order office was "open", the board would be set to "stop"
(the "default" position). Red paddles displayed crosswise to the track.

An approaching train would "call for signals" (4 short whistle blasts) then if
there were no orders, the operator would "clear" the signal to the white aspect
and let the train proceed. Engineman would acknowledge this with two short
whistle blasts & keep 'em rolling .

If there were orders for the train, the operator left the signal
set at the "stop" aspect, and went out on the platform with a yellow flag
by day or a white lamp at night and signaled the train ahead against
the signal to hand up the orders & clearance to the head end and the
trainman (conductor or brakeman). Hogger would answer his "come ahead"
with two short whistle blasts & have his fireman grab one order hoop, and
the trainman behind would grab the other. Operator retained a third copy of
the orders and clearance for train order office records.

Or something like that.....The rules varied some on different roads.