|relation domain part |
|relation range part |
|relation stencil |
A defined entity-relationship between parts.
An internal class that should never need to be directly used within application code.
If an entity e1 is a member of part m_root and there exists a relation from entity e1 to entity e2 that is in the domain of the relation stencil m_function then entity e2 is a member of part m_target .