If you are executing your rules in debug mode or the rules were interrupted by an error, this command shows were rule execution currently stopped. If it stopped in a subrule, all calling rules are also shown.
debug> trace line 23 in file "dmm-deutsch.syn", rule "fill_valencies" line 391 in file "dmm-deutsch.syn", rule "main_clause_end"This means, rule execution stopped in line 23 of `` dmm-deutsch.syn'', in rule `` fill_valencies''. This subrule was called from line 391 in `` dmm-deutsch.syn'', in rule `` main_clause_end''.