Domains are created from a list of 3D primitives, and subdomains from list of 3D primitives that are also contained in a domain. Assemblies and 3D composites can also be used as locations for domains and subdomains. In this case, all 3D primitives contained within the assembly or 3D composite are included in the domain.

Assemblies and 3D primitives not included in a domain are not used in the simulation. A 3D primitive may be implicitly included if it forms part of a 3D composite or assembly that is used in a domain.

The domains in a multi-domain simulation must be continuous or connected via domain interfaces - you cannot have separate isolated domains.