Do you mean using the Restrictive Airspace function?
If so, when you build your polygon/circular avoid area, you have three options available to you:
Alert - This will create an airspace incursion alert within the body of the flightplan.
Restricted - Will attempt to optimise the route, avoiding the restricted airspace either laterally or vertically.
Unspecified - This will create the restricted airspace and allow flights to pass through it without creating alerts.
On the Route & Time tab you can also change the way Restrictive Airspace affects your flight by selecting one of the following:
Enable CCAA - This will attempt to optimise the route whilst avoiding the restricted airspace either laterally or vertically.
Enable CCAAN - This will create an airspace incursion alert in the flightplan.
Hope that is some help...
