The user management is based on independent rights, not on levels. Each right can be assigned a bit number in CpStudio. The HMI activates the bits of the Rights variable in the HmiUtilAddon (or State struct) corresponding to the rights of the current user.
The rights used in the data editor are indeed a bit special: The HMI user administration dialog does not allow to assign them individually, so they behave like authorization levels. Technically, they are independent rights though, so a user with maximum access has all the lower-level data access rights as well. These rights are defined in the NxDataSetManagerAddon. You can look up their bit numbers in Data by category -> User Management in the STD area.
All other project-specific rights are displayed with checkboxes in the HMI user management, so they can be assigned independently.
