We have these classes in ISIM like erRole, erPersonItem. What does er stand for? Just used as prefix or does it mean entity relation or something?
The er in the class names is a reference to the old Access 360 enRole product that IBM purchased and rebranded Tivoli Identity Manager (now of course Security Identity Manager). It was used to identity classes that were used by the enRole product years ago.
There is a tiny bit of that history documented here if you are interested: https://ldapwiki.com/wiki/IBM%20IDM