;; definition of names of types with a special meaning to PET special-name-top := "*top*". special-name-symbol := "string". special-name-string := "string". special-name-cons := "cons". special-name-list := "list". special-name-nil := "null". special-name-difflist := "diff-list". ;; same for attributes special-name-attr-first := "FIRST". special-name-attr-rest := "REST". special-name-attr-list := "LIST". special-name-attr-last := "LAST". special-name-attr-args := "ARGS". ;; status values that marks rules rule-status-values := rule. lexrule-status-values := lex-rule. ;; status values that marks lexicon entries lexentry-status-values := lex-entry. ;; path to the list of arguments in a rule rule-args-path := ARGS. ;; path to marker for key argument of a rule keyarg-marker-path := KEY-ARG. ;; path to marker for head dtr of a rule head-dtr-path := HEAD-DTR. ;; path to orthography orth-path := STEM. ;; type to mark boolean value `true' true-type := +.