| G: | SECTION G PHYSICS |
| G11: | INFORMATION STORAGE |
| G11B: | INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER |
| G11B27/00: | Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel |
| G11B27/10: | . Indexing; Addressing; Timing or synchronising; Measuring tape travel |
| G11B27/19: | . . by using information detectable on the record carrier |
| G11B27/24: | . . . by sensing features on the record carrier other than the transducing track |
| G11B27/26: | . . . . by photoelectric detection, e.g. of sprocket holes |
