What is Machiokuri in Japanese Katana terminology?

The term "Machiokuri" (区送り, まちおくり) refers to a method of shortening the blade of a Japanese sword. In this process, the end of the tang (Nakagojiri) is left as is, while the Hamachi (刃区, the edge of the blade) and Munemachi (棟区, the ridge of the blade) are polished and shortened. When a sword undergoes Machiokuri, the length of the blade decreases, resulting in a longer tang. This method allows for the preservation of the original tang, which often carries the swordsmith's signature and other important historical information.