Specify a semicolon separated list of server version names, e.g. RTC/2.8;RTC/2.9, to which Office Communicator allows logon ...

"Specify a semicolon separated list of server version names, e.g. RTC/2.8;RTC/2.9, to which Office Communicator allows logon in addition to the server versions that are supported by default. Space character is treated as part of the version string."