1984 – Thailand Specimen revenues 1 baht and 20 baht with perfins and phosphor tagging. Thomas De La Rue Specimen stamps issued September 1984. Specimen is by perfins reading “TDLR Specimen” In addition to the perfins, the stamps are phosphor tagged, visible under UV light. The tagging reads 41/2527′ This stands for 41 printing 2527 or 1984. This number is repeated some 100 times on each stamp Scan 2 shows a typical sample (20 baht stamp 36/2521) how the tagging looks like under UV light.