My 2-cents deciphering "FP1" located on Tabinta/Boschfontein/President Grant Ship Movement Cards.
From the GLOSSARY OF U.S. NAVAL ABBREVIATIONS OPNAV 29-P1000 (Revised APRIL 1949) FIFTH EDITION Prepared by OFFICE OF NAVAL RECORDS AND HISTORY OFFICE OF THE CHIEF OF NAVAL OPERATIONS NAVY DEPARTMENT * WASHINGTON, D.C.APRIL 1949.http://asisbiz.com/Il2/US-Navy-Naval-Abbreviations.html
"FP -- Freight and Passenger Vessels (Army)" url:
The '1' probably assigned by the Convoy & Routing (C&R) and this number represents a specific movement of convoys and probably marked on C&R maps to track movements. I have not seen it repeated again on any of my SMC's.
Previously we see the Fleet designation convoy numbers like PW2111; which means 'Westbound Pacific Ocean Convoy' and 2 represents 12 US Naval District. The rest of the numbers are probably mapping routs. Without these maps used by the C&R or SOS we will never know the exact routes.
From Chapter III, Ocean Convoys, Section D, Pacific; United States Naval Administration in World War II, History of Convoy & Routing, Headquarters of the Commander and Chief, United States Fleet and Commander Tenth Fleet, Navy Department, Washington DC. 1939-1942, Secrete FX-37.