In Reply to: Guard rings and ground planes posted by Gillian on 06/13/02 at 8:49 AM:
Those guard rings are intended as protection against inadvertant conduction of current to the protected pins from whatever else the pins are surrounded by. That protection will be afforded against what ever things share a board layer in common with the foils leading to those pins.
Adding ground plane or rail voltage planes to other layers will not change the need for the aforesaid guard rings. Those planes will serve other purposes. The rings should be kept!