The original Hornbostel/Sachs system had 4 categories:
1. Idiophones - Instruments that vibrate themselves such as a xylophone 2. Membranophones - Instruments that have a vibrating membrane such a as a drum. 3. Chordophones - Instruments with vibrating strings 4. Aerophones - Instruments which incorporate vibration of air.
In this example of a woodblock print, the registration points, or chosen locations that ensure the colors align correctly, were likely placed in the corners by the artist.
