Hi,
I think that the origin of the commonly accepted division in series is from the drawings of Voronin, that report details of different variants listing the serie on which they appeared. This division was adopted by the
Lagg-3 in action monograph, and is widely accepted even if it contains by sure some simplifications, as the absence of indications of how the non mentioned series were, or the influence of the plant of building.
I think that, in spite of the doubts, being this classification widely accepted and sintetic, it is useful all the same for our purposes.
Massimo