Improve documentation of interactive "r".

* doc/lispref/commands.texi (Interactive Codes): Mention that mark
must be set for "r" to work.

diff --git a/doc/lispref/commands.texi b/doc/lispref/commands.texi
index b2dc49391b64785c68a7e1cf80425b378d0680d5..3710ee4caf79a57cb3a7d199d17d9cbea73ee8ee 100644 (file)
--- a/doc/lispref/commands.texi
+++ b/doc/lispref/commands.texi
@@ -484,7 +484,8 @@ I/O.
 @cindex region argument
 Point and the mark, as two numeric arguments, smallest first.  This is
 the only code letter that specifies two successive arguments rather than
-one.  No I/O.
+one.  This will signal an error if the mark is not set in the buffer
+which is current when the command is invoked.  No I/O.
 
 @item s
 Arbitrary text, read in the minibuffer and returned as a string