itchō 一丁

Lit. one chō 丁. One folded page of a printed book during the Edo period. Because only one side of a sheet was printed the sheet was then folded in half with the printed surface outward. The loose edges of the folded sheets were sewn together at the spine leaving the fold uncut on the outside, which might be considered the reverse of Western practice. The number of chō in a traditional printed book was thus equal to the number of folded sheets of paper assembled before binding.