- You may be looking for Obverse Books.
One implied that the Obverse was a construction of the Celestis' making. (PROSE: The Taking of Planet 5) Mathara believed that the Obverse was "a temporal boil on the flesh of the cosmos" created after the timelines were twisted by the Third Doctor getting infected with the Faction Paradox biodata virus. (PROSE: The Ancestor Cell)
The Obverse was connected to N-Space by the Enclave. Another entrance to the Obverse was located through a Ringpull on Hyspero. The Clockworks resided in the Obverse, from their powerbase in Saga City. (PROSE: Wildthyme Beyond!)