1V/oct, or one volt per octave, is the standard way most modular systems represent pitch. Each additional volt of control voltage raises an oscillator by one octave, so a change of 1/12 volt (about 83 mV) is one semitone.
Keyboards, sequencers, and quantizers send pitch CV in this scale, and oscillators with a 1V/oct input track it. Some vintage instruments use other standards, such as Hz/V.
