| 1630.2 | Classes. |
| 1630.10 | Class 1-A: Available for unrestricted military service. |
| 1630.11 | Class 1-A-0: Conscientious objector available for noncombatant military service only. |
| 1630.12 | Class 1-C: Member of the Armed Forces of the United States, the National Oceanic and Atmospheric Administration or the Public Health Service. |
| 1630.13 | Class 1-D-D: Deferment for certain members of a reserve component or student taking military training. |
| 1630.14 | Class 1-D-E: Exemption of certain members of a reserve component or student taking military training. |
| 1630.15 | Class 1-H: Registrant not subject to processing for induction. |
| 1630.16 | Class I-O: Conscientious objector to all military service. |
| 1630.17 | Class 1-O-S: Conscientious objector to all military service (separated). |
| 1630.18 | Class 1-W: Conscientious objector ordered to perform alternative service. |
| 1630.26 | Class 2-D: Registrant deferred because of study preparing for the ministry. |
| 1630.30 | Class 3-A: Registrant deferred because of hardship to dependents. |
| 1630.31 | Class 3-A-S: Registrant deferred because of harship to dependents (separated). |
| 1630.40 | Class 4-A: Registrant who has competed military service. |
| 1630.41 | Class 4-B: Official deferred by law. |
| 1630.42 | Class 4-C: Alien or dual national. |
| 1630.43 | Class 4-D: Minister of religion. |
| 1630.44 | Class 4-F: Registrant not acceptable for military service. |
| 1630.45 | Class 4-G: Registrant exempted from service because of the death of his parent or sibling while serving in the Armed Forces or whose parent or sibling is captured or missing in action status. |
| 1630.46 | Class 4-T: Treaty alien. |
| 1630.47 | Class 4-W: Registrant who has completed alternative service in lieu of induction. |
| 1630.48 | Class 4-A-A: Registrant who has performed military service for a foreign nation. |