Currently, depending on which tab Annotate or Sketch, or on which function, sketch, note, etc., certain entities cannot be selected for references.
For example, when creating a note, it's leader cannot be attached to a symbol, only the model object or sketches. However, the note cannot be related to an object type sketch, only to other notes or symbols.
Also, when sketching, axis, geometry, datums cannot be used for functions like mirror.
Why not just make all entities, object, draft, sketch, symbol, format, -EVERYTHING- selectable for everything else? Why add extra code to differentiate?
PTC, please make all entities selectable as references.