Let there be n variables in the SVAR (in DCN n = 6 and it is an SVAR(2)). Using the worksheet pre-numbered by the DCN is one option. On the research side, DCN is a testbed for a variety of communications technologies, methodologies and organizational strategies. With electronic filing, preparers must maintain total control over each client's file from the moment of the file's creation until both the file and DCN are accepted.