topology.IsValid*(TopoGeometry)

[strk]

TopoGeometry objects are references into a topology's structure. Such references may become dangling if the referee is destroyed.

Hierarchical TopoGeometry objects may be defined to be formed by overlapping lower-level compoments. Such composition should likely be also seen as an invalidity.

Non-hierarchical TopoGeometry objects may refer to missing primitives (corrupted topology).

Beside these structural invalidities there's likely no way for a TopoGeomety?-derived Geometry to be invalid.

[strk]

Following the rules under topology. this function shouldn't start with ST_ as it's not an ISO/SQLMM function. BTW, SQL/MM doesn't even have the concept of a TopoGeometry.