Variable: prolog-atom-char-regexp
prolog-atom-char-regexp is a variable defined in prolog.el.gz.
Value
"[[:alnum:]_$]"
Documentation
Regexp specifying characters which constitute atoms without quoting.
Source Code
;; Defined in /usr/src/emacs/lisp/progmodes/prolog.el.gz
(defconst prolog-atom-char-regexp
"[[:alnum:]_$]"
"Regexp specifying characters which constitute atoms without quoting.")