The Primary AuthID is the AuthID used to identify a process to XDB. Primary AuthIDs, and must be registered through the SQL Wizard (Windows) or Interactive SQL Utility (UNIX). They are typically used with a password to verify that the user is actually entitled to use that particular AuthID. Note that while a Primary AuthID is usually associated with an individual, it might be used by a group of people. For example, if several users will be using a system at different times, they might all be able to log on using the same AuthID and password.
Generally, it is recommended that each individual who accesses the system be assigned a unique AuthID and password. In this way the system is able to maintain more accurate records of who is actually using the system, and password security is more effective because the passwords are not shared. If security is off, the default Primary AuthID stored in the client configuration is used for internal system identification. This default can be modified through the Options Utility.