The change made in this addendum allows the use of R744 as a secondary coolant or refrigerant in certain situations. It allows limited releases of R744 to the atmosphere during unusual events, such as an extended power failure with coincident heat gains that would otherwise cause system pressures to rise above component design pressures. Refrigerant vented to atmosphere during a power failure is likely to be a "de minimus" quantity compared to losses from other causes such as normal leakage in even the best maintained commercial and industrial systems.