x-open-connection

x-open-connection is a built-in function in `C source code'.

(x-open-connection DISPLAY &optional XRM-STRING MUST-SUCCEED)

Open a connection to a display server.
DISPLAY is the name of the display to connect to.
Optional second arg XRM-STRING is a string of resources in xrdb format.
If the optional third arg MUST-SUCCEED is non-nil,
terminate Emacs if we can't open the connection.
(In the Nextstep version, the last two arguments are currently ignored.)