We all can agree that the UWZ book was ruhed and many mistakes were made, things were omitted do to size of book, and verbage was changed on accident on some things. And I think we can agree that the basics have generally stayed the same from 1st to 3rd edition. I still feel the meaning of Wait has not changed since 1st edition I feel the verbage is allowing for different interpations. Here's the definition from the 1st edition main rulebook page 58 where Wait was clearly spelled out so there couls be no missinterpation.
Wait: When a model is waiting, it is doing nothing except waiting and watching so that it can react to the foe. You can spend an action for a model to wait. If you do so, the model's turn ends. Place a waiting marker beside that model and continue with the rest of your turn.
Basically, a waiting model has 1 action in reserve, which it can use *out of normal turn sequence.* If an enemy model preforms any visible action within LOS, then the wating model can use its saved action.
If you are waiting, you can interrupt an enemys movement at any time. Once your waiting model has taken its action, remove the waiting marker. your opponent completes his turn as normal.
You do not have to take the action as soon as an enemy model moves into your LOS. You can wait until the entire unit comes closer. *Once the enemy squad or individual finishes its turn, though, you cannot act against it.*
I believe it was the same in second edition too, but My rules of war is not handy at this time when I find it I'll check. No where does it say you can use a wait during your turn, and clearly states its an reaction.
I understand its a different edition but only minor verbage changed. If the verbage was coorect the UWZ book reads as a reaction. Just a thought for when this is offically FAQ'ed