Dear Nagaraju,
In the case of ARs, the AR document do not get cancelled when a billing is cancelled, instead AR document gets cleared. So only status is changed when cancellation takes place.
Therefore there is no need of 0CANCEL required to indicate that the particular AR is cancelled.
But 0recordmode is required as there can be changes that gets recorded within one AR document for eg change in assignment field, text field etc
Regards
Gajesh
