status.i4.v = wn_circular_arc_c(x.r4.v, y.r4.v, radius.i4.v,
					start_angle.i4.v, arc_length.i4.v)

	This routine draws a circular arc at virtual coordinates X,Y 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 arc is determined by the most recent
	call to wn_color(_c).  The width of an unfilled arc is determined
	by the most recent call to wn_border_width_c.  Whether the arc is
	filled or not is determined by the most recent call to

	x, y		real world coordinates of the center of the circle
			containing the arc
	radius		radius of the arc in pixels
	start_angle	starting angle of the arc in degrees counterclockwise
			from the 3 o'clock position
	arc_length	length of arc in degrees

	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;
	int	radius = 5;
	int	start_angle = 90;
	int	arc_length = 180;
	float	x = 3.0;
	float	y = 3.0;

	status = wn_circular_arc_c(x,y,radius,start_angle,arc_length);