toplevel "A";
"A" and "T1" "B3";
"T1" or "B1" "B2";
"X" seq "B1" "B2" "B3";
"B1" lambda=0.5 dorm=0.3;
"B2" lambda=0.5 dorm=0.3;
"B3" lambda=0.5 dorm=0.3;