Reason for the format of the vehicle licence

Hello everyone, who has a registration certificate part 1, so the new version of the vehicle registration, you might have noticed that these dashed lines have printed on the “correct folding”. If you stick to them, you get a small and two large pages. A question that has been around me for some time, and which the ADAC could not answer: why is the first page smaller than the pages 2 and 3? So far I have assumed that the I could not find an “official” explanation. It can’t be related to the place for the registrations, because they could also be organized differently in order to get the necessary place. Does anyone have an official or official explanation? Thank you, Julian