Hi guys,
in a game I had this situation:

Attack the BZ with:

Wilhelm of the Osterknacht (Action: When this unit attacks, move one unit from the defending Zone to another Zone controlled by the same player.) And I want to play his Action on unit "X" in BZ to move in KZ.

The defender responds with:

Iron Discipline (Action: Target one unit. Until the end of the turn, cancel any other action that targets this unit unless the action's controller pays an additional 4 resources per action) on unit "X" in BZ.

In my opinion Iron Discipline does not protect the unit "X" by the action of Wilhelm as the action does not require the specific target which subsequently acquire that status, but speaks only of a “one unit “ (it’s a choise).
On the contrary Iron Discipline requires that the unit has the status of “target” to be able to "protect" canceling the action/s, not having, in this case the action of Wilhelm passes.

I would like a confirmation.

You need the word "target" in the text for ID to work against it. Willy doesn't have target in his ability, though some have wondered if there was supposed to be. Hence some confusion as to whether it is actually the defender who choose which unit and which zone.

Thanks for the quick reply confirming my interpretation, however, is always who controls Wilhelm who chooses Unit and Zone because the action say "move"