Class D: Planetoid, moon or asteroid. Examples include Regula and Rura Penthe.

Class C: Small Rocky Planetoid - Similar to Gothos

Class L: Habitable planet that supports primitive life. This can be very simple fauna, or even life as advanced as a Bronze Age culture.

Class M: Earth-like both in its size, core, and age as well as in the advancement of the native creatures. Class M worlds are frequently the home of sapient races capable of traveling in space.

Class M: Earth-like both in its size, core, and age as well as in the advancement of the native creatures. Class M worlds are frequently the home of sapient races capable of traveling in space.