The scope of the project is the interfaces between existing Gas Insulated Substations (GIS) equipment and gas insulated equipment that is added at a later date, and may be of a different design. The project includes the interfaces at Gas Insulated Transmission Line (GITL) equipment, and Gas Insulated Substations (GIS) equipment. Interface practice is not currently covered by a consensus document. This document will recommend practices, for both users and suppliers, for identification of, and solution to, interface problems. New IEEE Standard - Inactive-Reserved. Reaffirmed 2004 Recommendations for the connection of a gas-insulated substation to another gas-insu- lated substation of a different make are given.