anchor.diff:    (auth :string)
     (host :string))
   
  -(defun open-connection (&optional key-filename host)
  -  "Open a new connection to BRLTTY on HOST usng KEY-FILENAME for authorisation.
  +(defun open-connection (&optional auth host)
  +  "Open a new connection to BRLTTY on HOST usng AUTH for authorization.
   Return a DISPLAY object which can further be used to interact with BRLTTY."
     (with-foreign-object (settings 'settings)
       (setf (foreign-slot-value settings 'settings 'auth)
  -          (if (stringp key-filename) key-filename (null-pointer))
  +          (if (stringp auth) auth (null-pointer))
             (foreign-slot-value settings 'settings 'host)
             (if (stringp host) host (null-pointer)))
       (let* ((handle (foreign-alloc :char :count (foreign-funcall "brlapi_getHandleSize" :int)))
  
positive.code: 
  ;;;; * TTY mode
  
  (defmethod enter-tty-mode ((obj display) tty &optional (how ""))
    (declare (integer tty))
    (declare (string how))
    (setf (slot-value obj 'tty) (foreign-funcall "brlapi__enterTtyMode" :pointer (display-handle obj) :int tty :string how brlapi-code)))
  
  (defmethod leave-tty-mode ((obj display))
    (foreign-funcall "brlapi__leaveTtyMode" :pointer (display-handle obj) brlapi-code)
  
negative.code:       (0 nil)
        (1 (mem-ref key 'key-code)))))
  
  (defun expand-key (code)
    (with-foreign-objects ((command :int) (arg :int) (flags :int))
      (foreign-funcall "brlapi_expandKeyCode"
                       key-code code
                       :pointer command :pointer arg :pointer flags
                       :int)
      (values (intern (foreign-funcall "brlapi_getKeyName"
  