I am using ESRI GeometryEnvironmentClass that implements IGeometryFactory3 and I use the method CreateGeometryFromWkbVariant. For the same wkb, in ESRI 9.3.1 the returned polygon is oriented clockwise, but in ESRI 10.0.0 it seems that it is counter-clockwise.
(I have found this out using the method IsSimpleEx in ITopologicalOperator3 interface: in 9.3.1 the polygon is simple, but in 10 it is not, with reason esriNonSimpleRingOrientation - "A polygon is topologically simple, but its rings may not be oriented correctly (outer rings - cw, inner rings - ccw)".)
Any idea what changed? Why was it working in 9.3.1 and no longer works in 10?