| Abbreviation | Definition |
|---|---|
| MMRFA | chinist's Mate (refrigeration Mechanic) Fireman Apprentice |
| MMRFA | Machinist's Mate (refrigeration Mechanic) Fireman Apprentice |
| MMRFN | chinist's Mate (refrigeration Mechanic) Fireman |
| MMRFN | Machinist's Mate (refrigeration Mechanic) Fireman |
| MMRFR | chinist's Mate (refrigeration Mechanic) Fireman Recruit |
| MMRFR | Machinist's Mate (refrigeration Mechanic) Fireman Recruit |
| MMS1 | chinist's Mate (shop Machinist) 1st Class Petty Officer |
| MMS1 | Machinist's Mate (shop Machinist) 1st Class Petty Officer |
| MMS2 | chinist's Mate (shop Machinist) 2nd Class Petty Officer |
| MMS2 | Machinist's Mate (shop Machinist) 2nd Class Petty Officer |
| MMS3 | chinist's Mate (shop Machinist) 3rd Class Petty Officer |
| MMS3 | Machinist's Mate (shop Machinist) 3rd Class Petty Officer |
| MMSR | chinist's Mate (ship Repair) |
| MMSR | Machinist's Mate (ship Repair) |
| MMSRE | chinist's Mate (ship Repair-engine) |
| MMSRE | Machinist's Mate (ship Repair-engine) |
| MMSRI | chinist's Mate (ship Repair-instrument) |
| MMSRI | Machinist's Mate (ship Repair-instrument) |
| MMSRO | chinist's Mate ((ship Repair-outside)) |
| MMSRO | Machinist's Mate ((ship Repair-outside)) |