upper left stamp in mint block of four (positions 48-49, 58-59), dark carmine overprint, stage V (12.Fa), additionally position 59 with "Pamana" reading up at left (12.7) and position 58 "N" with double diagonal stroke in right "Panama" (12.20), very fine and attractive block, 1990 Philatelic Foundation certificate (Scott $150 for 12b)