User administration

Does anyone know where I can find information how to differentiate between a domino system administrator and a user administrator?In the past we always assigned our user administrators the same permissions as the system administrators but I really would like to change that.

Subject: use ACL in names.nsf

you need Author access & [UserCreator][UserModifier] roles for persons who will perform registration and recertification tasks.Also recomended to create Notes Certification Authority for all cert.id file used and set them as Registration Adinistrators.