A definition of factorial effects relying on the treatment structure defined by the hierarchies is proposed. It applies to non uniform situation, where the number of levels of a nested factor within the classes defined by each set of levels of its nesting factors may vary. A reparametrisation whose parameters belongs to these factorial effects is obtained. The development is based on the notion of orthogonal reference treatment design, a conceptual design that can be used as a basis of comparison to asssess the properties of any factorial design.