| 984 / | HD | MUSICAL INSTRUMENTS |
| 250 | DD | AIDS FOR MUSIC (metronomes G04F 5/02; teaching music G09B 15/00) {G10G} {4} |
| 251 | | .~ Means for the representation of music {G10G 1/00} {2} |
| 252 | DD | .~.~> Chord or note indicators, fixed or adjustable, for keyboard or fingerboards {G10G 1/02} |
| 253 | DD | .~.~> Transposing, transcribing {G10G 1/04} |