You issued an ADDDATASET or a CHANGEDATASET subcommand with a RETPD, EXPDT, or LASTREF operand for a file which is not the first file of the volume set. RMM detects that the data set resides on a volume managed by the EXPDT retention method with the RETAINBY(FIRSTFILE) attribute. The data set will get the new expiration date or LASTREF attribute assigned, but the effective expiration date of the volume is unchanged as long the first file of the volume set is not changed.