German to English Tech/Engineering Architecture windows

An 18th-century inventory description of a building in Holstein contains the following: "Die fünf von außen angenagelten und eine Rahmen Fenster mit Anwurff und ••Hacken•• sind in passablen Stande." and "In dieser Kammer ist ein altes Rahmen Fenster ohne Anwurf und ••Hacken••.
I think this is an old spelling of Haken.
I understand Anwurf as plaster and I have asked about Rahmenfenster in a separate query. Since I also don't know exactly what kind of window this is, it is hard for me to choose the right term for Haken. A colleague suggested it might be a hook, but I can't picture this window. Bucksch equates Haken with Rinnenziegel and Nonnenziegel (mission tile), but it doesn't seem to be in a window context. Is anywone familiar with this term? I have checked the 1902 Muret-Sanders and the online Grimm's Wörterbuch, but I'm still wandering in the dark. Thanks for your help.