Hey everyone. I've purchased a Honeywell digital programmable (5-1-1)
and I am totally lost with the wiring. My old mercury t-stat had only
two wires, a red and a white, with no labeling on the wires or the wall
plate. The new one has a bunch of lettered wire spots (W, C, RC, Y,
etc.) and they say in the manual not to choose based on wire color -
but I have nothing else to go on.

Help please!