I remember being driven absolutely crazy by a guy (who hopefully won't read this) who called me every other week and asked me how to stick a page break into some text file he was writing. He was only printing on a garden-variety daisy wheel printer, for which inserting a page break is a simple matter: just add a formfeed character, CTRL-l. But CTRL-l already means something to Emacs ("redraw the screen"). How do you get the character into your file, without Emacs thinking that you're typing a command?
Simple. Precede CTRL-l with the "quoting" command,
CTRL-q. CTRL-q tells Emacs that the next character you
type is text, not a part of some command. So the sequence
CTRL-q CTRL-l inserts the character CTRL-l
into your file; you'll
You can use this technique to get any "control character" into an Emacs file. In fact, under pressure I've done some pretty bizarre binary editing - not a task I'd recommend, but certainly one that's possible.