The ':sescape' keyword is an entry used in the *readtable* system variable that contains XLISP's data structures relating to the processing of characters from the user [or files] and read-macro expansions. The existance of the ':sescape' keyword means that the specified character is to be used as a single escape character. The system defines that the the backslash character '\' is the only defined ':sescape' character.
;; define a function to look in a table
;; and print out any :SESCAPE character
(defun look-at (table)
  (dotimes (ch 127)
    (prog ((entry (aref table ch)))
      (case entry
        (:SESCAPE (princ (int-char ch)))
        (t nil))))
  (terpri))
(look-at *readtable*)    ; prints  \
Caution: If you experiment with *readtable*, it is useful to save the old value in a variable, so that you can restore the system state.
See the
:sescape
keyword in the