security tables e.g. _user

I am trying to gain a better understanding of progress/openedge database security and I have read that _USER table lists database accounts and permissions etc. My query is if a server hosts multiple openedge databases, is there a _USER table per database, or is it a similar concept to Microsoft SQL Server, where you have an instance, and a set of user database, and system databases, and the system databases include the security configurations for the whole instance.