The status of the indexed shelf in the GSX9000 node. If the value
of this object is not accepted(3) or shuttingDown(4), then the objects
in Sonus Shelf Status table are unavailable. The value of this object
does not reach accepted(3) until after the slave shelf has contacted
the master shelf, and has successfully joined the node. A value of
shuttingDown(4) indicates the shelf will be unavailable shortly.