| 1/00 | General design |
| 1/02 | General design of organs |
| 1/04 | General design of organs electrically operated |
| 1/06 | General design of organs fluid operated |
| 1/08 | General design of harmoniums |
| 3/00 | Details or accessories |
| 3/02 | Details or accessories Blowers |
| 3/04 | Details or accessories Reservoirs |
| 3/06 | Details or accessories Valves; Sleeves |
| 3/08 | Details or accessories Pipes, e.g. open pipes or reed pipes |
| 3/10 | Details or accessories Actions, e.g. coupler |
| 3/12 | Details or accessories Keys or keyboards; Manuals |
| 3/14 | Details or accessories Pedals or pedal boards |
| 3/16 | Details or accessories Swell chambers; Accentuating means |
| 3/18 | Details or accessories Tremolo-producing devices |
| 3/20 | Details or accessories Transposing devices |
| 3/22 | Details or accessories Details specially adapted for electrically-operated organs, e.g. contacts therein |