<Geographical Area Description> ::=
	<Point> |
	<Point with uncertainty circle > |
      <Point with uncertainty ellipse> |
	<Polygon> |
	<Point with Altitude> |
	<Point with altitude and uncertainty ellipsoid> |
	<Arc>;
<Point> : :=
	0000 <spare>(4)
	<Point horizontal co-ordinates> ;
<point horizontal co-ordinates> ::=
	<Latitude sign : bit> <Unsigned latitude : bit string(23)>
	<Longitude : bit string(24)> ;
<Point with uncertainty circle > ::=
	0001 <spare>(4)
	<Point horizontal co-ordinates>
	<spare bit> <Uncertainty: bit string(7)> ;
<Point with uncertainty ellipse> ::=
	0011 <spare>(4)
	<Point co-ordinates>
	<spare bit> <Uncertainty semi-major: bit string(7)>
	<spare bit> <Uncertainty semi-minor: bit string(7)>
	<Orientation of major axis: bit string(8)>
	<spare bit> <Confidence: bit string(7)>;
<Polygon> ::=
	0101 <Number of points>
	<Point co-ordinates>(val(Number of points)) ;
<Number of points> ::=
	0011 | 0100 | 0101 | 0110 | 0111 | 1000 | 1001 | 1010 |
	1011 | 1100 | 1101 | 1110 | 1111 ;
<Point with Altitude> ::=
	1000 <spare>(4)
	<Point horizontal co-ordinates>
	<Point vertical co-ordinate>;
<point vertical co-ordinate> ::=
	<sign : bit> <Unsigned altitude : bit string(15)>
<Point with altitude and uncertainty ellipsoid> ::=
	1001 <spare>(4)
	<Point horizontal co-ordinates>
	<point vertical co-ordinate>
	<spare bit> <Uncertainty semi-major: bit string(7)>
	<spare bit> <Uncertainty semi-minor: bit string(7)>
	<Orientation of major axis: bit string(8)>
	<spare bit> <Uncertainty altitude: bit string(7)>
	<spare bit> <Confidence: bit string(7)>;
<Ellipsoid Arc> ::=
	<1010> spare(4)
	<Point horizontal co-ordinates>
	<Inner radius: bit string(16)>
	<Spare bit> <Uncertainty radius: bit string(7)>;
	<Offset angle: bit string(8)>
	<Included angle: bit string(8)>
	<spare bit> <Confidence: bit string(7)>;
<Velocity Description> ::=
	<Horizontal Velocity> |
	<Horizontal and Vertical Velocity> |
	<Horizontal Velocity with Uncertainty>|
	<Horizontal and Vertical Velocity with Uncertainty>;
<Horizontal Velocity> : :=
	0000 <spare>(3)
	<Bearing: bit string(9)>
	<Horizontal speed: bit string(16)>;
<Horizontal and Vertical Velocity> : :=
	0001 <spare>(2)
	<Vertical direction : bit>
	<Bearing: bit string(9)>
	<Horizontal speed: bit string(16)>
	<Vertical speed: bit string(8)>;
<Horizontal Velocity with Uncertainty> : :=
	0010 <spare>(3)
	<Bearing: bit string(9)>
	<Horizontal speed: bit string(16)>
	<Uncertainty Speed: bit string(8)>;
<Horizontal and Vertical Velocity with Uncertainty> : :=
	0011 <spare>(2)
	<Vertical direction : bit>
	<Bearing: bit string(9)>
	<Horizontal speed: bit string(16)>
	<Vertical speed: bit string(8)>
	<Horizontal Uncertainty Speed: bit string(8)>
	<Vertical Uncertainty Speed: bit string(8)>;