When I started with the project “builds out of my comfort zone”, and accordingly started to scrutinize the manuals from the nickel-era, I soon realized that using manual numbers for the models would grow very confusing, due to that numbers changing from booklet to booklet, depending of the editing year and/or the country were they were published. So, I decided to rather classify the models, according to a "categories" or “types” system of my own. As usual when developing things, adjustments and corrections occur on the way and, therefore, the classification of the models from here on vary a bit in comparision with the criteria adopted in the former drawer. Note: As late as in the 50´s manuals, some numbering changes still occurred, so that I will keep my system till 1961, just before the exploded-views, multilingual manuals appeared (which seem to have been uniform through all countries)