wn_box(_c)

	status.i4.v = wn_box(x1.r4.r, y1.r4.r, x2.r4.r, y2.r4.r)

	status.i4.v = wn_box_c(x1.r4.v, y1.r4.v, x2.r4.v, y2.r4.v)

	This routine draws a rectangle at the specified real-world
	coordinates in a graphical window specified by a previous call
	to wn_active(_c).  wn_view(_c) and wn_world(_c) must also be
	called before calling this routine.  The color of the rectangle is
	determined by the most recent call to wn_color(_c).  The width of
	an unfilled rectangle is determined by the most recent call to
	wn_border_width_c.  Whether the rectangle is filled or not is
	determined by the most recent call to wn_fill_mode(_c).

	x1, y1		real world coordinates of one corner of box
	x2, y2		real world coordinates of diagonal corner of box

	This function returns ACNET status values as follows:

	OK			success
	CBS_NOSETUP		an active window has not been established

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	wn_color(_c), wn_user_defined_color_c, wn_read_user_defined_color,
	wn_fill_mode(_c), wn_border_width_c, wn_flush, intro_graphics_windows

	C/C++ usage:

	int	status;
	float	x1 = 3.0;
	float	y1 = 3.0;
	float	x2 = 8.0;
	float	y2 = 8.0;

	status = wn_box_c(x1,y1,x2,y2);