There has been quite a lot of argument and discussion on various internet fora regarding the correct use of the Zornhau in the Nach, that is, when being used to counter an Oberhau. Is it used to strike the opponent's sword (with a follow-up technique immediately afterwards), or is it to be used to strike his sword and his head in one motion--a "single-time cut with opposition"?
I have written a brief paper on this subject, to include pictorial demonstrations, which I believe definitively settles this question. It can be found on the die Schlachtschule web page by clicking this link: Some Observations on the Zornhau
As always, I welcome any responsible comments or questions.