From MoodleDocs
  • This is implemented for backward compatibility. It is flag to tell Moodle that this role is an admin role.
  • This does NOT provide a role with all capabilities of a pre-Moodle 1.7 admin. All admin capabilities must be individually allowed.
  • Note: It is not necessary to allow any legacy capabilities unless using old 3rd party code that was not designed for Moodle 1.7 and doesn't yet support roles.