What causes the LASTUPDOPRID and LASTUPDDTM field on PSOPRDEFN (User Profile)?

We have PeopleSoft Security Officer who does all the security changes in PeopleSoft.  We are seeing that users have a different OPRID and Last Update Date/Time than that of the security officer.  Most of the time it is same OPRID as the User Profile we are looking at.  I know changing your password will update these fields, however we use a single sign-on so users do not update passwords within PeopleSoft itself. For audit reasons we need to explain these userid/time, the process that updates, and fields affected.

Thank you!