I am replacing my Weathertron BAY28x138A thermostat with a Honeywell RTH 3100C thermostat. It is on a Trane XL1200 Heat Pump with Aux. and Emerg. Heat. The terminals and colors of wire are as follows on the Weathertron:

O-Orange
R_Red
T-Brown
G-Green
Y-Yellow
X2-Black
B-Blue
U-Jumper to W
W-White
F-Blank

The terminals on the Honeywell RTH3100C are as follows:
E, Aux, Y, G, O, L, R, B, C.

I could use help in determining which wire to hook to what and as near as I can tell the T-Brown is not used on the new thermostat.