A database system and method allows a user to write program code in a high-level programming language that implements a class that defines the structure of a user-defined type and methods that can be invoked on instances of the type. The present invention uses pinch-off of a JFET, controlled by an inverter, to control a backup power supply based on the availability of the main supply. The donor monomer composition includes one or both of isobutylene and diisobutylene, and the acceptor monomer composition includes acrylic monomers and monomers containing functional groups. Exemplary rules may define a modification to the zone group identifier to be associated with a PHY of the expander based on the present operating status of the expander.