Controls the (VCF) filter's envelope levels. This controls how the filter shapes the "brightness" of the sound over time). If a MultiTimbral device, then each Part usually has its own patch with its respective VCF cutoff frequency that can be adjusted with this controller.
Note: There are other controllers for adjusting VCA attack and release times, and other generic sound parameters.
0 to 127, with 0 being minimum setting.