From Version 9 you can use this feature to remove levels from your report, which can be useful when drilling.
Note that when skipping levels, members of those levels will not be shown, even when directly selected in the grid.
In this example, we have a hierarchy that contains:
And we want to skip past the semesters, and go directly to the quarters.
The result is that when we drill years we next see quarters
We will make the same changes in a slicer, remembering to select "Use query restrictions for children".
the result is a tree that again goes directly from year to quarter.