For the m_sSurfaceDomain member, the face domain for the usage of the surface; must be included in surface’s domain. If not defined (that is, invalid domain with Min > Max), the face domain is the surface domain.
When parsing an A3DTopoFaceData structure, use a tolerance that is the greater of these values:
A3DTopoContextData::m_dTolerance member for the entity
A3DTopoFaceData::m_dTolerance member for the entity
Outer loop index. A3D_LOOP_UNKNOWN_OUTER_INDEX
If the outer loop index is exactly equal to the number of loops in a surface, it should not be used as an index in the loops array (since the index is zero-based, it will be out of range). In this case, it refers to an implicit outer loop corresponding to the parametric domain bound.This can happen on closed surfaces when inner or outer loops have no meaning in the 3d space; the implicit outer loop allows users to still have an outer loop representing the outer bound of the surface parametric dimension.