Several methods require a value for the sid, or server ID, parameter. Note that this is different from the system_id. You may determine the sid of a machine in two different ways. First, you can log into the RHN website, click the name of a system, and view the sid at the end of the URL in the location bar. It will be after the equal (=) sign in something like, "index.pxt?sid=1003486534". Second, you may use the list_user_systems method within the system class to obtain a list of systems available to the user that contains the associated sids.