Arturia KeyStep Pro Keyboard with Advanced Sequencer and Arpeggiator - Manual (Page 82)

5.3.1.3. Mono and Poly
In Mono mode, a sequencer will only play one note per step. In Poly mode, a sequence can
play up to 16 notes per step. To switch modes, hold down 'Shift' and press the Mono key (D#
in the lower octave) or the Poly key (E in the lower octave).
You can use this Shift function in a performance by switching a polyphonic sequence to
monophonic. However, only the lowest note of the chord will survive. You can also do this
the other way around by starting in Mono mode and suddenly re-introducing chords by
switching to Poly mode.
When recording in Mono mode, the KeyStep Pro will only allow you to store one note in a
step, whether it is in Quick Edit, Step Edit or Real Recording mode. This makes it easier to
record bass lines.
New patterns you create in Mono mode will always record with Overdub OFF.
In Drum mode, Mono mode means that all 24 tracks share the same length. In Poly mode,
each track can have a separate length.

♪ : When Poly is active, Lst Step operations (copy, extend) only affect the currently selected track.
76 Arturia - User Manual Keystep Pro - Making Tracks