wn_getworld(_c)

	status.i4.v = wn_getworld(plane.i4.r, screen_coord.i4.r,
				  world_coord.r4.r)

	status.i4.v = wn_getworld_c(plane.i4.v, screen_coord.i4.v,
				    world_coord.r4.r)

	This routine returns a world coordinate given a screen (pixel)
	coordinate for the active graphic window.

	plane		(WN_HORZ -> horizontal,
			 WN_VERT -> vertical)
	screen_coord	screen (pixel) coordinate
	world_coord	returned world coordinate

	This function returns ACNET status values as follows:

	OK			success
	CBS_INVARG		invalid plane value passed
	CBS_NOSETUP		an active window has not been established
	CBS_RANGE		pixel is not located in the active window

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	wn_getscrn(_c), wn_view(_c), wn_active(_c), wn_world(_c),
	intro_graphics_windows

	C/C++ usage:

	int	status;
	int	plane = WN_HORZ;
	int	screen_coord = 320;
	float	world_coord;

	status = wn_getworld_c(plane,screen_coord,&world_coord);