Void Syntax Coverage. Where exactly 3 values are specified, they are interpreted as x, y, R . Where exactly 4 values are specified, they are interpreted as x, y, z, R .
R is a radius value in the same scheme.
Where z values are not specified, the x,y pairs form an ordered set defining the edge of a polygon in an anticlockwise direction. Where z values are specified, the region is defined as the minimum convex hull enclosing all x,yz triples. Region and Coverage. Void elements may be repeated. In decimal and fractional notation, approximate precision of the data shall be indicated by the number of decimal places.