In assembly drawings you can insert geometric tolerances in the top-level assembly, the subassembly, or in a part.

When you create a geometric tolerance in the top-level model (that is, a part in a part drawing or top assembly in an assembly drawing) the system associates the tolerance with the view in which you have selected a reference entity. Reference datums that you specify for the geometric tolerance must belong to the same top-level model; however, you can select them in any view. You cannot reference draft entities and draft datums.

Geometric tolerances applied to draft entities (draft geometric tolerances) can reference datums of the model. You can attach an assembly geometric tolerance to a dimension, datum, or another geometric tolerance, provided they both belong to the same assembly.