The 1:3 section is a buffered multiple, allowing a note CV to be distributed to up to 3 VCOs without voltage drop.
The 2:2 section is a 2-input summer with unity gains (also known as a precision adder). The sum of the two input channels is distributed to 2 outputs.
The 3:1 section is a 3-input mixer, with a gain of 1⁄3 per channel (also known as an averager). It is particularly suitable for rapidly mixing audio sources such as oscillators, for which a unity gain mixer would have caused clipping.
Input impedance: 1M for the buffered multiple, 100k for the mixers.
Buffered multiple with low offset error.
0.1% resistors, allowing the 2:2 section to work as a precision adder.