Final answer:
Applicants for the Medical Enlisted Commissioning Program (MECP) must not have reached their 42nd birthday by the time of initial appointment and commissioning to be eligible.
Step-by-step explanation:
The MECP (Medical Enlisted Commissioning Program) is a pathway for enlisted service members in the military to earn an appointment and commissioning as a nurse corps officer. Applicants to the MECP must meet various eligibility requirements, including age restrictions. Typically, applicants must not have reached their 42nd birthday by the time of their initial appointment and commissioning. This ensures that candidates can have a sufficient career span as officers and meet the mandatory retirement age regulations in military service. It is always best to check the most current guidelines issued by the specific branch of service as they may be subject to change.