Seeking explanation of USS General C. C. Ballou (AP-157) WWII Troop Ship Passenger List Code. My father left Calcutta on this ship and arrived in New York City on 6 November 1945. He had served in various capacities in the CBI Theater. In the scan from the "Incoming Passenger Manifests and Alien Crew Lists," port of New York from 5 November 1945 to 6 November 1945, he is listed on the page titled, "U.S. Army Patients -- Class 4." I am trying to find out what that designation means, along with the codes by his name "1D/B" and "MD." My guess is that "MD" might refer to "Medical Detachment" as, at times, he did serve as a medic. Is there a resource that I can use to decipher these codes?