x-server-vendor

x-server-vendor is a built-in function in `C source code'.

(x-server-vendor &optional TERMINAL)

Return the "vendor ID" string of the X server of display TERMINAL.
(Labeling every distributor as a "vendor" embodies the false assumption
that operating systems cannot be developed and distributed noncommercially.)
The optional argument TERMINAL specifies which display to ask about.
TERMINAL should be a terminal object, a frame or a display name (a string).
If omitted or nil, that stands for the selected frame's display.