PostGIS 1.5.8 Manual - Fedora Project Packages GIT repositories

PostGIS 1.5.8 Manual27 / 310(e) (f) (g)(e) and (f) are simple MULTILINESTRINGs, (g) is not.By definition, a POLYGON is always simple. It is valid if no two rings in the boundary (made up of an exterior ring and interiorrings) cross. The boundary of a POLYGON may intersect at a POINT but only as a tangent (i.e. not on a line). A POLYGON maynot have cut lines or spikes and the interior rings must be contained entirely within the exterior ring.(h) (i) (j)