* doc/emacs/basic.texi (Basic Undo): Explain the C-/ situation in xterm

AFAICT, in ttys you can send a `C-_` to Emacs either by pressing
`C-/` (e.g. xterm, uxterm, rxvt, xfce4-terminal, gnome-terminal)
or by pressing `C--` (e.g. rxvt, Linux console).

diff --git a/doc/emacs/basic.texi b/doc/emacs/basic.texi
index fc856a3acb765a1506ede77e7a846a4d37470546..2e03d0c04a31eb9a2766c15cf022e990ed5c61ce 100644 (file)
--- a/doc/emacs/basic.texi
+++ b/doc/emacs/basic.texi
@@ -467,10 +467,11 @@ changes in the buffer; you can't use it to undo cursor motion.
   On a terminal that supports the @key{Control} modifier on all other
 keys, the easiest way to invoke @code{undo} is with @kbd{C-/}, since
 that doesn't need the @key{Shift} modifier.  On terminals which allow
-only the ASCII control characters, @kbd{C-/} does not exist, but many
-of them allow you to omit the @key{Shift} modifier when you type
-@kbd{C-_} (in effect pressing @kbd{C--}), making that the most
-convenient way to invoke @code{undo}.
+only the ASCII control characters, @kbd{C-/} does not exist, but for
+many of them @kbd{C-/} still works because it actually sends @kbd{C-_}
+to Emacs, while many others allow you to omit the @key{Shift} modifier
+when you type @kbd{C-_} (in effect pressing @kbd{C--}), making that
+the most convenient way to invoke @code{undo}.
 
   Although each editing command usually makes a separate entry in the
 undo records, very simple commands may be grouped together.