An interface is provided to handle mouse events.
Mouse drivers are available for SUN-TOOLS (``emacstool'' from GNU-EMACS)
and for X-Windows (supplied mouse_type).
The recognized mouse events are:  Left Click:  set text cursor.  
Middle Click:  set text cursor, then insert a gap
The mouse data should be presented as the following string:
.sp
``\\030\\000(KeyCode MouseX MouseY)\\n''
.sp
where ``\\030'' is octal character code 030 (CAN), ``\\000''
is the null character, and MouseX and MouseY reflect the mouse position
in character units (upper left is 0,0).
MouseX, MouseY, and KeyCode are reported as decimal numbers.
The KeyCode is complex, made up of bit fields.
the bits are:
.RS 4
.PP
.TP 8
    Bit 0:  Left Button Event
    Bit 1:  Middle Button Event
    Bit 2:  Right Button Event
    Bit 3:  Shift key was down
    Bit 4:  Control key was down
    Bit 5:  Meta key was down
    Bit 6:  Shift Lock key was down
    Bit 7:  ``0'' when Button Pressed, ``1'' when Button Released
.RE