(Read Only Buffers): Mention optional ARG to `toggle-read-only'.

diff --git a/lispref/buffers.texi b/lispref/buffers.texi
index 0eee01d980dbcd644e099e3d60f986c588ca2e88..723dae742ab3f610c62a75655b27e576d920aa50 100644 (file)
--- a/lispref/buffers.texi
+++ b/lispref/buffers.texi
@@ -737,12 +737,17 @@ properties have no effect.  If @code{inhibit-read-only} is a list, then
 of the list (comparison is done with @code{eq}).
 @end defvar
 
-@deffn Command toggle-read-only
-This command changes whether the current buffer is read-only.  It is
+@deffn Command toggle-read-only &optional arg
+This command toggles whether the current buffer is read-only.  It is
 intended for interactive use; do not use it in programs.  At any given
 point in a program, you should know whether you want the read-only flag
 on or off; so you can set @code{buffer-read-only} explicitly to the
 proper value, @code{t} or @code{nil}.
+
+If @var{arg} is non-@code{nil}, it should be a raw prefix argument.
+@code{toggle-read-only} sets @code{buffer-read-only} to @code{t} if
+the numeric value of that prefix argument is positive and to
+@code{nil} otherwise.  @xref{Prefix Command Arguments}.
 @end deffn
 
 @defun barf-if-buffer-read-only