The description of Ansetzen in the glosses falls between the Vier Versetzen and Nachreisen, and seems to fall somewhere in between conceptually. The Vier Versetzen act in the moment of the attacker's action, and the Nachreisen act in the moment after, the Ansetzen occur (at least according to Pseudo von Danzig) the moment before the opponent attacks as he moves from guard to guard in preparation (in fact in modern fencing terms we might call the technique an attack in preparation).
The key elements of the Ansetzen are the use of the point and seeking the 'nearest' opening before the opponent has the opportunity to attack. The broader principle behind this is expressed well by Lew:
"and as soon as he lifts up his sword and will strike-around, you shall immediately fall into the point and thrust to the nearest opening. But if he will not go with the sword, then you yourself shall go with your sword, and as soon as (or every time as) you end a strike, fall Meanwhile into the point every time. If you can execute the setting-on correctly, then he must balance or shift himself hard. It must allow you a wound."
The following application gives but one possible example of the Ansetzen, however the technique can be used at any time when the opponent draws themself into a position for an immediate attack. In the words of the Pseudo von Danzig gloss:
"If he will then hew above or stab below, then mark while he lifts up his sword and will strike, or pulls it to himself below and will stab, and then come Before and shoot the long point into the nearest opening before he brings ahead his hew or stab, and see if you may Set-on him. Likewise do that also when he hews to you with Under-hews: then shoot the point in before he comes up with the hew from below, and drive that to both sides."
|Pflug, left leg forward||Pflug or Ochs, left leg forward|
|Lift to right Vom tag and shift wait as if about to strike.||Shoot the point forward to his left side (covering the likely line of attack)|
|Continue the attack following with the point or cutting around.|
Notice as they move to their upper right we attack the left opening, likewise if they moved to the upper left we would attack the right opening, and so on.
There is no canonical description of the Ansetzen in Meyer, however the movement is described implicitly throughout all of the weapons & especially when Nachreisen is being described.