Chord Track (BIAB term as of 2025) - Set of usually simplified MIDI block chords derived from main chords of your arrangement, with very specific set of rules and options that can be defined in settings. It is mainly used to drive either arpeggio type synths, Midi phrase or sample phrase based VST instruments, which reinterpret those block chords to seamless backing to your composition and commonly utilize "Key Switches" (2025 BIAB addition - preserve range) for variation, intonation and whole bunch of other things.

There are two main "types" of Chord Tracks currently available in BIAB.
1 - activated in settings and pointed to particular track - it always "picks up" any changes you are making to chords automatically
2 - Generated on any track per right click. It takes current arrangement chords and creates MIDI block chords. It will not pickup changes automatically, but is fully editable.

Both types (auto and single use) have separate purposes.

There is more to that, but this is essential purpose of these. Range rules, certain modified simplification, and manually set range preservation makes them very distinct from your average MIDI track.