The Identity Memo for Determination of Fitness (IMDF) is a document to refer the servicemen to government restructured hospitals/polyclinics for the determination of their fitness only. Each IMDF can be used for only one visit and is only valid for one month from the date of issue, or up till the serviceman's last day of service (i.e. service completion date), whichever is earlier. Servicemen must ensure that the appointment date for the medical examination is scheduled within the IMDF validity period.