OGC valid polygon

According to OGC SFS (Implementation Standard for Geographic information - Simple feature access - Part 1: Common architecture, version 1.2.1) in a valid polygon "No two Rings in the boundary cross and the Rings in the boundary of a Polygon may intersect at a Point but only as a tangent". So the POLYGON ((0 0, 0 10, 10 10, 10 0, 5 0, 3 3, 5 6, 7 3, 5 0, 0 0)) seems to be OGC valid. Why GeometryValidator treats it as invalid?