Fundamental modelling parts of the network

Hi there,
Is there any documentation/models on the fundamentals? I’m struggling to see these.
The models at the moment I’m looking for relate to

- Taps - Is a tap required per phase/neutral or a single tap with a phase attribute. Having a tap per phase seems a bit excessive and it clutters the network.

- Crossarms - With the new related table, how do you model crossarms related to structure junctions (eg. Poles) and more importantly relate them to the line? The main sequence of relationships is electric line supported by a crossarm which is supported/structural attachment to the pole. This type of relationships is required to be used by interfaces to EAM systems.
Also, how to model crossarm relationships to other features (eg. EDO fuse mounted on it)

- Are there any restrictions on the amount and types of relationships between features? Can a record in a related table be part of containment (eg. A crossarm part of a pole mounted substation)?

Thanks