[from here (http://community.livejournal.com/damned/631176.html?view=53406344#t53406344)]

Youko ducked into the first branching hallway and looked at the nearest room numbers: M40, M39. The hallway after that had M30 and M29. So the numbers were getting smaller as one went north and west within this block--M57 wouldn't be here. Back the way she came, then.