Grundstellung
The Grundstellung was the starting position of the Enigma rotors, part of the daily key and the first step in every encryption session.
In the German Enigma procedure, the rotors were first set to a starting position, the Grundstellung, before any encryption began. It consisted of three letters and came from the daily key sheet. Because operators used it to encrypt the message key, it was a key to the whole procedure, not just a preliminary step.
The Grundstellung is not the same as the ring setting, which was a fixed offset of the rotors' alphabet rings and changed less often. The distinction matters because a rotor can have the right starting position while the ring setting is wrong, and the other way round.