In NN-XT grouping allows you to organise your zones when multi sampling. In this example I have created an NN-XT patch which combines bass and piano samples.

In order to separate these two sets of samples/zones I select all the bass zones. Then I right click for the drop-down context menu and select Group Selected Zones. Now I have two groups of zones (bass and piano), divided by a horizontal white line that runs the length of the keyboard.

Now when I need to adjust the group parameter settings to all my piano samples all I need to do is left click below the white line in the vertical bar directly to the left of the sample names.

To move zones from one group to another simply click on the zone name and drag it into the relevant group. To move groups click and drag in the group bar

Group parameters are settings shared by all the zones in a particular group. The group parameter controls can be found in the top left corner of the Remote Editor. For these parameters to affect the group it must first be selected.