| Abbreviation | Definition |
|---|---|
| MMLFN | chinist's Mate (general) Fireman |
| MMLFN | Machinist's Mate (general) Fireman |
| MMLFR | chinist's Mate (general) Fireman Recruit |
| MMLFR | Machinist's Mate (general) Fireman Recruit |
| MMMB1 | chinist's Mate (motor Boat) Petty Officer First Class |
| MMMB1 | Machinist's Mate (motor Boat) Petty Officer First Class |
| MMMB2 | chinist's Mate (motor Boat) Petty Officer Second Class |
| MMMB2 | Machinist's Mate (motor Boat) Petty Officer Second Class |
| MMO1 | chinist's Mate (optician) Petty Officer First Class |
| MMO1 | Machinist's Mate (optician) Petty Officer First Class |
| MMO2 | chinist'e Mate (optician) Petty Officer Second Class |
| MMO2 | Machinist'e Mate (optician) Petty Officer Second Class |
| MMR1 | chinist's Mate (refrigeration Mechanic) 1st Class Petty Officer |
| MMR1 | Machinist's Mate (refrigeration Mechanic) 1st Class Petty Officer |
| MMR2 | chinist's Mate (refrigeration Mechanic) 2nd Class Petty Officer |
| MMR2 | Machinist's Mate (refrigeration Mechanic) 2nd Class Petty Officer |
| MMR3 | chinist's Mate (refrigeration Mechanic) 3rd Class Petty Officer |
| MMR3 | Machinist's Mate (refrigeration Mechanic) 3rd Class Petty Officer |
| MMRC | chinist's Mate (refrigeration Mechanic) Chief Petty Officer |
| MMRC | Machinist's Mate (refrigeration Mechanic) Chief Petty Officer |