USERS
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Details - Users are listed here. You can add new or edit existing user here. When adding new user you can assign him to group or set his rights.
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Can delete - user can delete report
Roles
Details - You can set roles details here. Add name and description.
Report in roles - You can add reports to role. All users that have that role automatically gain access to reports in role.
Users in role - U can add users to role here. All users added inherit reports selected in that role.