CL – CLX

(xlib:open-display "" :display 0)
;; → #<XLIB:DISPLAY :0 (The X.Org Foundation R12101003)>
(xlib:open-display "" :display 1)
;; → #<XLIB:DISPLAY :1 (The X.Org Foundation R12101003)>
(xlib:open-default-display)
;; → #<XLIB:DISPLAY :0 (The X.Org Foundation R12101003)>
(xlib:open-default-display ":1")
;; → #<XLIB:DISPLAY :1 (The X.Org Foundation R12101003)>

(xlib::get-display-modifier-mapping (xlib:open-default-display))
;; → ((65506 . 1) (65505 . 1) (65507 . 4) (0 . 8) (0 . 8) (65511 . 8)
;; (65041 . 16) (65407 . 16) (65517 . 32) (0 . 64) (0 . 64) (65516 . 64)
;; (65406 . 128) (65027 . 128))

(XLIB::DISPLAY-KEYBOARD-MAPPING (xlib:open-default-display))
;; an (UNSIGNED-BYTE 32) array, 256x32