Filtering Controllers
You can filter out the most commonly used MIDI controllers for each slot separately.
For example, if you set up a keyboard split with bass and piano playing on the same MIDI channel, both sounds receive the same MIDI controllers. However, you usually do not want the bass to receive the sustain pedal. To avoid that all sounds on the same MIDI channel receive the same MIDI controllers, use the controller filter.
Filtering out control change messages can also be used to avoid unwanted program changes on MIDI channel 10 (drums), for example.