net controleur
tr A1 : App far*3 -> far*2 in Coming 
tr A2 : App far in -> in*2 
tr D : Down [0,0] Coming -> 
tr E1 : Exit [0,0] far*2 in -> far*3 Leaving 
tr E2 : Exit [0,0] in*2 -> far in 
tr U : Up [0,0] Leaving -> 
pl far (3)
