Best I can figure is that it's some form of cryptography. The "severed" thing would be to compartmentalize even more what the underlying work is, the outties are clueless, but even the innies don't get to know what they do because the work is encrypted. They're able to perform it because another part of their brain is severed even more, and just performs the raw algorithm work of decrypting/sorting.
But the rest of Lumen just seems like some bizarro "there's a spaceship hiding in the tail of the comet" cult.
But the rest of Lumen just seems like some bizarro "there's a spaceship hiding in the tail of the comet" cult.