The top-level URL of the system. If it does not exist the value is empty string. The URL format is implementation dependant and can have keywords embedded that are preceeded by a percent sign (eg, %USER). The following are the defined keywords that will be recognized and replaced with data during a launch. USER - replace with username PASSWORD - replace with password GLOBALID - replace with globalid SERIALNO - replace with serial number If write is not supported, then return invalid. This value will be retained across boots.