a__zeros cons 0 zeros a__tail cons X XS mark XS mark zeros a__zeros mark tail X a__tail mark X mark cons X1 X2 cons mark X1 X2 mark 0 0 a__zeros zeros a__tail X tail X a__zeros 0 cons 2 0 0 zeros 0 a__tail 1 mark 1 tail 1 INNERMOST ./TRS/TRCSR/inn/Ex4_7_77_Bor03_GM.trs