Thanks for the help..it was helpful
Job's done..
Two more steps are involved:
1) Deleting the M version entries of infoobject, to which reference charactersistic has to be set say, OBJ1 in tables RSDCHABAS,RSDBCHATR,RSDATRNAV,RSDATRNAVT.
2) Setting Activfl field in RSDIOBJ from X to Space for all versions of OBJ1.
SAP note 568051 discusses this in details..