I use the null character in GNU screen: escape ^@^@ On most keyboards, you can enter it with control-space, which is very easy to type and rarely used for

I use the null character in GNU screen: escape ^@^@ On most keyboards, you can enter it with control-space, which is very easy to type and rarely used for other purposes (though emacs uses for `set-mark-command`). Control-] can also be a good choice (at least for US-style keyboards that don't require shift for the square brackets).