The relationship between brep.Faces(i), brep.Curves3D(j), brep.Curves2D(j)

We know that brep perhaps has many Faces(i)(base surface), but how to know Curves3D(j) or
Curves2D(j) belong which Faces? could anyone tell me? your help will be appreciated.

See this page. Even though it is for c++ you get the relationship between faces, trims, loops, etc.

http://developer.rhino3d.com/guides/cpp/brep_data_structure/

Link seems to be down. Is there any other link to see that Brep data structure?

Someone replaced underscores with dashes and broke the link. In all the posts that it is in. :angry: