Integration with Other Applications > Windchill Workgroup Manager Documentation > SolidWorks > Advanced Techniques > Assembly Membership > Required versus Optional Dependents
  
Required versus Optional Dependents
In Windchill Workgroup Manager, explicit meaning is assigned to the two types of dependent relationships, required and optional. Required has two meanings:
The dependent is required to completely define the set of interrelationships between objects in Windchill.
The dependent is necessary for successful retrieval of the object in SolidWorks.
Optional means that the dependent is not necessary for successful retrieval of the object in SolidWorks. For example, a suppressed component is optional in an assembly (in general, the only optional members of an assembly are suppressed components). However, if the component is resumed, it becomes a required dependent.
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Whether a dependent is required or optional can depend on the configuration retrieved from Windchill. Also be aware that you are not prevented from removing a required assembly member from the list of objects being retrieved; however, removing a required member may require your intervention in the SolidWorks session to complete retrieval.
For example, consider a SolidWorks assembly p.sldasm. At iteration A.1 it includes components 1.sldprt, 2.sldprt, and 3.sldprt. All 3 components are considered required.
In iteration A.2 of p.sldasm, 3.sldprt has been suppressed. Components 1.sldprt and 2.sldprt are considered required. Component 3.sldprt is considered optional.
In the case when the CAD application provides you a choice in whether to retrieve related objects, these are optional dependents.
For example, if you create a feature in 1.sldprt using 2.sldprt and save, when opening 1.sldprt you are given a choice to open 2.sldprt also. As it is a user choice to open 2.sldprt, it is an optional dependent of 1.sldprt.