CAD11 — Model Instances vs. Top-Level Entities

The distinction between model instances and top-level entities was unclear to me, especially so given my task of trying to write a general purpose tool to "import" arbitrary CAD models into CFD-GEOM via the CAD Services interface. A Model can contain zero or more ModelInstances, and this provides support for assemblies. At the same time, certain entities in a Model are designated as top-level entities, which also brings to mind the concept of a composition or assembly.

Additional text is needed in the documentation