U.S. Stamps - Transportation Issues FDC Collection - 51 Cachet First Day Covers
HR - Hinge Remnant. NGAI - Unused, no gum as issued (special printing). OG - Original gum. DOG - Original gum, disturbed. POG - Part original gum. F/VF - Margins reasonably clear on all sides. VF - Very well-centered, POF.