Composite reference designators are used to track the relative location of a subassembly or part in the System Tree Items table. When you generate or update composite reference designators, Composite Reference Designator stores the reference designators associated from the top-most item down to the selected item as a single entity. This display-only field can be inserted in the System Tree Items table or Parts Table or on a custom Prediction Assemblies or Prediction Parts form. Composite reference designators can be generated or updated at any time.

The following figure shows a portion of a system tree that contains System Tree Identifier, Reference Designator, and Composite Reference Designator columns. The composite reference designator for a system tree item is generated by stepping down from the top-most item to that item. Colons separate the reference designators for each tree level. If you change reference designators or insert tree items after composite reference designators are generated, you should repeat the procedure in this topic.