What is Chiri in Japanese Katana terminology?

The term "Chiri" (散, ちり) refers to the flat area on a Japanese sword that lies between the groove (Hi: a long, narrow trench carved into the blade) and the ridge (Mune: the opposite side of the blade), or between the groove and the ridge line (Shinogisuji). If there is a Chiri on both sides, it is referred to as "Ryochiri" (両散). If it is only on the side between the groove and the ridge line, it is called "Katachiri" (方散). This terminology is used to describe the specific characteristics of the sword's structure, contributing to its overall aesthetic and functional design.