The PAYMENT PERIOD in title XVI cases is generally the 48-month period immediately
            preceding 12/91 (i.e., 12/87 through 11/91). However, if eligibility and disability
            continue, benefits may continue beyond the “PAYMENT PERIOD.” Certain exclusions listed below will affect the PAYMENT PERIOD.
         
         The FO is responsible for computing the PAYMENT PERIOD and potential onset prior to
            sending the case to the DDS. The PAYMENT PERIOD will be computed using the DEVELOPMENT/PAYMENT
            PERIOD Worksheet (DI 12586.095, Exhibit 10), or the PC program, if available in the FO.