Ableton's Span transformation gives you two ways to reshape MIDI note lengths in a chord pattern: an Offset control that lengthens or shortens all notes relative to their current values, and a variation parameter that introduces differences across individual notes. Before applying these, you choose a starting expression, Tenuto (original lengths), Legato (lengthened), or Staccato (shortened), which sets the baseline the transformation works from. Used together, Offset and variation add movement and tension to patterns that might otherwise feel static.