Security levels normally in use aboard a Federation starship are:
Level 10 – Captain and Above
Level 9 – First Officer
Level 8 - Commander
Level 7 – Lt. Commander
Level 6 – Lieutenant
Level 5 – Lt. Junior Grade
Level 4 - Ensign
Level 3 – Non-Commissioned Crew
Level 2 – Civilian Personnel
Level 1 – Open Access (Read Only)
Note: Security Levels beyond current rank can and are bestowed where, when and to whom they are necessary.
The main computer grants access based on a battery of checks to the individual user, including face and voice recognition in conjunction with a vocal code as an added level of security.