Level 1 planet was a designation of intergalactic law, similar to other known designations including level 2, 4, 5 and 6 planets.
The virtual planet Eden 2 held level 1 class, with sentences of a thousand years hard labour being imposed on those who attempted to conquer it. (COMIC: Freeze)
The War Doctor once described level 1 technology as "beyond the Dark Times." (AUDIO: The Neverwhen)