
At the limit or edge is the unknowable. The diagram for this is a circle or (if you don't care for the myth of pure geometry) an island like an amoeba whose skin ripples and fluctuates. This border's elasticity is the reach for the unknowable.
But in the fictional cartography of China Mieveille's writings the unknowable is often interior to mapped geography. The cacotopic stain, an unstable delusive zone that defies comprehension, blotches out a portion of the world like the focus of a wormhole and can only be traversed around by the characters, lest they disappear from the storyline. The map is riddled with lacunae, but they are not gaps of knowledge, they are holes in the real.
This gives the hyper-real a new totem, as a dense, tightly controlled and ideal geometrical unit. Reality, on the other hand, is still quite porous.