Mado

Window. Small Shiroji areas occurring either in Hi plates or Sumi patched that look like windows. This Shiroji in Hi plates is also called Madoaki. It is considered a weak point because the Mado rarely fill in and they disturb the dignity of the pattern. If they help keep the total balance of the pattern then they may be considered acceptable. Mado can be caused by the inborn character of the Koi or from being damaged and/or missing scales.

(Courtesy of the excellent Book Kokugyo Vol II)