When you install the Addr-Type object, you must add information to the site proxy address field (the Gateway-Proxy attribute) of the site object. This means that you are adding another value to the multivalued Gateway-Proxy field (for proxy addresses) of the site object. The Gateway-Proxy field for each site contains information that proxy generation DLLs use to create addresses for the users at that site. This site object should have one proxy address for each Addr-Type object installed; this also means that it has one proxy address for each address template installed.