Integration with Other Applications > Windchill Workgroup Manager Documentation > NX > Advanced Techniques > Assembly Membership > General Description of Member Functionality
  
General Description of Member Functionality
In its simplest form, a member is an object that has been included in a grouping of objects. When the grouping includes multi-level relationships, the structure will be displayed in the appropriate PDM report. Information regarding whether an object is required or optional is stored on the member link between CAD documents, as it is specific to an assembly context.
* 
Required or optional membership in the structure is not the only criteria for collecting components for model structures. If a structure component has external references that are required, these references are also included in a collection of structure-required dependents. For more information on external references, see Overview of External References.
Windchill Workgroup Manager defines the following types of members for assembly relationships:
Member -- A component of an assembly, whether a discrete component or sub-assembly component.
Construction member -- A member of an assembly whose prime purpose is to simplify user actions in the assembly context. Construction members do not contribute to the Bill-of-Materials (BOM).
Substitute member -- A member that has been substituted in an assembly for simplification purposes (for example, a simplified version of a finished part.