Yes, so maybe I like reblogging Robert Yang's posts. Like, a lot. But the point is: he writes good stuff. In this case, it is about level design. And in my opinion, it is pretty clever idea.
Based on a presentation by Randy Smith on "Level Building for Stealth Games", Robert Yang creates a system do design levels based on valence.
In this way, Randy Smith's "valence theory" (NOTE: again, he never called it that, but I am) posits that different parts of a room or level can afford stealth mechanics: level elements can have a POSITIVE [+] valence (shadowy, quiet, stealth-friendly) or NEGATIVE [-] valence (bright, noisy, not stealth-friendly).
Scattering those elements with their valence over the level can give you an overview of how the level will be traversed.