Wings in the MAtricks are used to separate the selection into the number of wings set and select devices from each wing from opposite directions.
It is better explained with examples.
In this example, there are ten fixtures (1 through 10).
They are selected from 1 to 10 without any specific grid information. Highlight is activated.
Since there is no grid information, then the fixtures are only in one axis - the X axis.
Press Next to make the MAtricks X value 0.
It looks like this in the Selection Grid and Fixture Sheet (Channel SheetMode) window:
Now tap + in the XWings in the MAtricks window to set the value to two.
Now it looks like this:
The selection is split into two wings and each end of the selection is currently On.
Use Next to change the X number up. This moves the highlighted selection towards the "center" of the selection. Prev moves out again.