active f X X mark f a b active b mark a active f X1 X2 f active X1 X2 f mark X1 X2 mark f X1 X2 proper f X1 X2 f proper X1 proper X2 proper a ok a proper b ok b f ok X1 ok X2 ok f X1 X2 top mark X top proper X top ok X top active X active 1 f 2 mark 1 a 0 b 0 proper 1 ok 1 top 1 INNERMOST ./TRS/TRCSR/inn/Ex16_Luc06_C.trs