What is Aoe Boshi in Japanese Katana terminology?

The term "青江帽子" or "Aoe Boshi" refers to a type of 'Boshi' (a term used in Japanese swordsmithing to refer to the temper line in the point of a Japanese blade) that is often seen in the works of Chū-Aoe, a blacksmith from the Aoe school during the middle of the Kamakura period to the early years of the Nanboku-chō period. The Aoe school was located in Bitchū Province, which is the western part of present-day Okayama Prefecture.