The Plan Region tool lets you define a region within a plan view that has a different view range from the overall view. Plan regions are useful for split level plans or for displaying inserts above or below the cut plane. Plan regions are closed sketches and cannot overlap each other. They can have coincident edges.
Example
The cut plane 
for a plan region in an elevation
Plan region in a floor plan
Plan regions are view-specific. You can copy and paste them into the same view or different views. When you copy a plan region into a different view, the view range settings are maintained from the previous view.
Plan regions export and print when they are visible in a view.