expression.IsSynchronous
expression Required. An expression that returns a Search object.
Remarks
If the search is synchronous, the user's computer will wait until the search has completed. Conversely, if the search is asynchronous, the search could still execute when the code has finished running. In this case, use the Search object's Stop method to halt the search.
In order to get meaningful results from an asynchronous search, use the AdvancedSearchComplete event to notify you when the search has finished.