Final answer:
Reporting to MPEAP is typically mandatory under specific circumstances as outlined by military or program policies, which could include changes in health or legal status affecting service or enlistment.
Step-by-step explanation:
The question seems to be inquiring about regulations related to the Military Personnel and Enlistment Applicant Processing (MPEAP) system or a similar program that requires certain information to be reported under specific circumstances.
Typically, the requirement to report to such systems is determined by the policies and guidelines established by the military or governing body that manages the program. It could involve situations like changes in applicant's health, legal status, or other factors that could affect their enlistment or ongoing service.
However, without more context, it is difficult to provide a concrete answer. The specifics of when to report to the MPEAP or a similar system are guided by the detailed policies of the program, which one should consult in the appropriate administrative or legal literature or resources.