| Subject | English | Japanese |
| snd.rec. | magnetic medium relative efficiency with respect to a reference magnetic medium | 磁気媒体の相対感度 |
| snd.rec. | recording head relative efficiency | 記録ヘッドの相対効率 |
| phys. | relative luminous efficiency | 比視感度 (hishi-kando) |
| snd.rec. | reverse relative tape efficiency | テープの往復感度差 |