Description: A Voltage notification is sent when a change is detected in the 5
volt backplane communication rails.  These backplane 
communication rails are used by the bay controller to
communicate with the occupant of a given slot.  There are 8
rails, each servicing the slots in one half of a shelf in the
bay (aviciBayVoltageIndex == rail):

 Rail   Slots
==============
  1    1 - 5
  2    6 - 10 
  3   11 - 15
  4   16 - 20
  5   21 - 25
  6   26 - 30
  7   31 - 35
  8   36 - 40

If the voltage is out of specification, the communication path
will not function.  When a given backplane communication channel
is not functioning, modules serviced by this rail cannot be
discovered (if a module is inserted) and will not be authorized
to boot (if an existing module reboots).  The current voltage is
reported in the aviciBayVoltage object.  A human readable
description of the event triggering this notification is
included in the aviciSysTrapDescr object.