creates a tty frame connected to the running emacs server. You can
use any number of different ttys. `emacsclient -c' creates a new X11
frame on the current $DISPLAY (or a tty frame if $DISPLAY is not set).
+There may be problems if a display exits unexpectedly and Emacs is compiled
+with Gtk+, see etc/PROBLEMS.
You can test for the presence of this feature in your Lisp code by
testing for the `multi-tty' feature.