Hi,
there is a new SCN Section which gives information about the SAP MaxDB User concept.
You'll get information about the different database user types, OS user in an SAP environment and configuration files which store user information ( upc-Container, xuser, SSFS)
https://wiki.scn.sap.com/wiki/x/ZBZiGg
Hope this information is helpful for you.
Regards, Christiane Hienger