Characters are printed as specified in [ANSI CL standard ] using #\, with one exception: when printer escaping is in effect, the space character is printed as "#\Space" when the variable CUSTOM:*PRINT-SPACE-CHAR-ANSI* is NIL. When CUSTOM:*PRINT-SPACE-CHAR-ANSI* is non-NIL, it is printed as "#\ "; this is how [ANSI CL standard ] specifies it.