To create a broken-out section view, place a closed polygon or circle overlapping an existing inserted view, then click on the Fragmental View icon on the palette toolbar.
Select the drafting object.
Select the closed 2D polygon or circular object that overlaps the drafting object. 
The Assembly list will now show a Fragmental View at the bottom of the list and in the Preview window, when selected.
You can now insert this view to your drawing. You can edit the 2D shape overlapping the drafting object and the inserted Fragmental View will update.
