This walkthrough from Ableton's Learn Live series breaks down the three zone editors inside an Instrument Rack: Key, Velocity, and Chain Select. Using a rack with bass, piano, and bell chains, it shows how dragging the edges of a Key Zone assigns each chain to a range of your keyboard, so low notes trigger bass, mid notes trigger piano, and high notes trigger bell, all in one rack.
The Velocity Zone editor works the same way but splits chains by how hard you play rather than which key you hit. A noise sample gets mapped to only fire when velocity hits 100 or above, a useful move for layering in dynamics like a snare rimshot or a synth transient that only kicks in on harder hits.
Chain Select zones let you fade or switch between chains manually or with automation, rather than tying the split to key or velocity at all. Dragging the upper handles crossfades smoothly between a fourth added instrument and the original three, and the chain select ruler at the top can be mapped to a Macro for real-time control during a set or mix.
All three editors share the same interaction logic: resize zones by dragging their sides, fade between them with the upper handle, and adjust the interface size through the context menu when you need more room to work.