toplevel "A";
"A" or "B" "C" "D";
"B" wsp "I" "M";
"C" wsp "J" "M";
"D" wsp "K" "M";
"I" lambda=0.5 dorm=0.3;
"J" lambda=0.5 dorm=0.3;
"K" lambda=0.5 dorm=0.3;
"M" lambda=0.5 dorm=0.3;