virtual_coord.r4.v = wn_text_coord_to_world_c(plane.i4.v,

	This routine converts a text coordinate into its corresponding
	world coordinate value.  The origin of the text coordinate system
	(0, 0) is in the upper left hand corner of the graphic window.

	plane		(WN_HORZ -> horizontal,
			 WN_VERT -> vertical)
	text_coord	text coordinate
	world_coord	returned world coordinate

	This function returns status values as follows:

	-1.0			conversion failed
	otherwise		virtual coordinate value

	This function requires the following include files:

	cbslib_h, acnet_errors_h

	Related functions:

	wn_text_coord_to_virtual_c, wn_view_text_format_c, wn_text_size(_c),
	wn_set_background_format_c, wn_set_background_size_c,
	wn_read_text_format, intro_graphics_windows

	C/C++ usage:

	int	status;
	int	plane = WN_HORZ;
	int	text_coord = 1;
	float	world_coord;

	status = wn_text_coord_to_world_c(plane,text_coord,&world_coord);