STEP - OpenCascade structure

[petrasvestartas]

Hi,

I am serializing a STEP using opencascade.
In a hierarchy of a written step, when we construct an assembly, there is always the following:

• root name > shape_definition_representation > shape_representation > context_dependent_shape_representation > actual geometry or subassembly.

Why these are always present and what do they stand for?

• shape_definition_representation
• shape_representation
• context_dependent_shape_representation