The administrator administrates system user list where he can also create a new user and assign particular role and group for the created user. User list and all covered functions are described in chapter 4.2 User list.
The administrator can also create new user groups or configure existing user groups by assigning different roles to particular user groups. User groups' administration is described in chapter 4.4 User group list.
Additionally, access control description is presented in a separate chapter and provides overall approach to the system access control through security levels (chapter 4.1 Access control).