I have put together the information that so many wonderful people shared, and done some research and testing of my own, and prepared a brief summary that others new to the Caen St. Etienne may find useful. Please feel free to comment and criticize.
The foot levers are numbered from left to right as seen on the Stops screen.
1) Orage - This acts as a key itself, requiring nothing else to be pressed. It plays preset low adjacent pedal notes using whichever stops are set. The result is a liver-rattling rumble that is perfect for accompanying Ride of the Valkyries.
2) Tir GO - G.O. to pedal coupler
3) P - Positif to pedal coupler
4) R - Recit to pedal coupler
5) Oves GO - G. O. Sub (16' coupler)
6) R - Recit Sub
7) Aches Ped - Must be down for Combinaison and d'Extension (red labels) pedal stops to play
Aches GO - Must be down for Combinaison (red labels) G. O. stops to play. Cop GO (#11) must also be down.
9) P - Must be down for Combinaison and d'Extension (red labels) Positif stops to play
10) R - Must be down for Combinaison and d'Extension (red labels) Recit stops to play
11) Cop GO - Must be down for ANY G. O. stop to play
12) P - Positif to G. O. coupler
13) R - Recit to G. O. coupler
14) R au P - Recit to Positif coupler. If Positif to Pedal coupler (#3) is also down, Pedal plays both manuals.
15) Trem - Tremelo on Recit
Tim