The MUPIP DOWNGRADE command currently changes the file-header to V4 format. The format of the MUPIP DOWNGRADE command is:
MUPIP D[OWNGRADE] file-name
It reduces the size from 8 bytes to 4 bytes for fields like current transaction (CTN), maximum tn (MTN) and others that contain transaction numbers.
It removes the results of any prior DBCERTIFY run on the database.
One cannot downgrade a V5 database which has standard null collation. In such a case, perform a MUPIP EXTRACT -FORMAT=ZWR operation on the V5 database and then perform a MUPIP LOAD operation on a V4 database.