Idflieg aircraft designation system

The Idflieg (Inspektion der Fliegertruppen/Inspectorate of Flying Troops) designation system was used to classify German heavier-than-air military (as opposed to naval) aircraft from the early days of the Fliegertruppe/Luftstreitkräfte to the end of World War I. The system evolved during this period as new classes of aircraft came into use. The specific, official "name" of a Luftstreitkräfte aircraft type consisted of the name of the manufacturer, the designation allocated to its class or category, and finally a Roman numeral.

Source: Wikipedia — Idflieg aircraft designation system (CC BY-SA 4.0)