Who keyed in that alternate pay rate?

How can you determine who keyed in an alternate pay rate via HR14.1?  We've got a case where someone or several someones are doing it incorrectly.  We'd like to see how and when is doing this but there is no datestamp/timestamp or userid column in the PRRATES table to do this with.  I've tried seeing if there was an OBJ-ID with another table but no dice.  Any suggestions as to how I can provide this information to my payroll management?