Here are some examples: ;; this works (find-variable-value '?s (unify #T(list ?f ?s) '(a (b c)))) ;; this works (find-variable-value '?s1 (unify #T(list ?f (?s1 ?s2)) '(a (b c)))) ;; this fails (find-variable-value '?s1 (unify #T(list ?f (list ?s1 ?s2)) '(a (b c)))) I was expecting the meaning of LIST to be the same whether it is encountered at top level in a template, or at a nested level. Is this a bug, or are my expectations wrong? -russ