centro de hoja or center of the sheet is a kind of cuban postage stamps where there are intersecting gutters between four panes of stamps. the horizontal and vertical blank gutters divide the sheet into quadrants of 25 stamps each. the center four or sixteen stamps on a sheet of 100 stamps are collected similar to how plate blocks of four stamps are collected in the united states. the first "centro de hoja" were the imperforate cuban patriots issues of 1926. these had the unique distinctions of being from sheets of 400 rather than 100 and the "gutters" consisted of nothing more than two intersecting lines drawn through the center of the sheet. the last was produced with the three bicentennial of coffee issues of 1952. some people classify the christmas issues of 1960 as centros de hoja, but since they have no gutters others call them "special format" stamps.