| Code | Explanation | From | Through |
|---|---|---|---|
| 0 | Not Required | 01/01/1970 | Present |
| 1 | Confidential. Executive Order 13526. | 09/01/2018 | Present |
| 2 | Secret. Executive Order 13526. | 09/01/2018 | Present |
| 3 | Top Secret. Executive Order 13526. | 09/01/2018 | Present |
| 4 | Sensitive Compartmented Information. Intelligence Community Directive 704 | 09/01/2018 | Present |
| 5 | Q. Atomic Energy Act of 1954. | 10/01/2018 | Present |
| 7 | L. Atomic Energy Act of 1954 | 01/01/1970 | Present |
| 8 | Other | 01/01/1970 | Present |