'Gakumei' (frame inscription) is a type of inscription in which a long sword is cut short and its original inscription on the cut part is embedded onto the sword as in a frame.
「額銘」は長大な太刀を磨上げ（すりあげ）して寸法を短くした後、磨上げ部分にあった元の銘を切り取って額のように嵌め込んだもの。