[wimcnqzf] Imminent power loss signal over power lines

Create a data protocol over power lines for signaling that there will imminently be a planned power outage.  Computers tuned to that signal through their power supplies can automatically initiate orderly shutdown procedures.  Or they can deliberately ignore the signal if there is too great a chance for a Denial-of-Service attack through this protocol.  Because this protocol communicates over power, the computer does not need to have other network capabilities.  It does seem that anyone can induce signal variation in the power lines can credibly shutdown power as well.

Less radically, create an internet-based protocol that a computer can subscribe to for power shutdown updates.  It should be hierarchical, covering larger and larger regions which might have a planned power outage.

Inspired by the difficulty of manually shutting down many computers prior to a planned power outage.