Required for proper septum positioning and septum construction during septation. Acts as a landmark to mark sites for future septation, and as part of a scaffold that recruits components of the contractile ring to the site of septation. Not required to determine the site of lateral branch formation. Localizes close to the hyphal tip and transiently localizes to septal sites. Initially forms a single ring which subsequently splits into two distinct rings as the septum forms, and disappears after septum completion. Belongs to the BUD3 family.