* doc/lispref/objects.texi (Special Read Syntax): Mention #f,
which is in cl-prin1 output (bug#55853).
Skip the next @samp{N} characters (@pxref{Comments}). This is used in
byte-compiled files, and is not meant to be used in Emacs Lisp source
files.
+
+@item #f
+Indicates that the following form isn't readable by the Emacs Lisp
+reader. This is only in text for display purposes (when that would
+look prettier than alternative ways of indicating an unreadable form)
+and will never appear in any Lisp file.
@end table