General post office imperforate proof, 30 sen in orange (instead of red), full printing sheet of 400 stamps wit horizontal an vertical gutters including a gutter block, only known sheet in this colour without numbers and letters in margins and written notes Gezien 28/11 1952 and fiat tjitak 1/12 '52, both with signature. Colour not mentioned in Zonnebloem or Prangko, some brown spots, an unique sheet!
