moritheil said:I am not in need of edification on the concept of initiative, though I thank you for taking the trouble to type that up. Rather, I have a memory of a passage in the DMG stating that the concept of initiative is not absolute with regard to the simultaneity of actions (or lack thereof) and that therefore certain actions that mechanically occur later may occur at the same time.
But then again the DMG is subserviant to the PHB when it comes down to questions of runnng combat.
Because of the possibility of actions not actually happening in the order described by initiative (which is, as you stated, a simplification), simultaneity is available as a possible explanation for extending the period of time during which one is considered "charging."
Using this basis of simultaneity, an AoO can never happen since everything happens at the same time (or roughly so). So a character can't step up and attack someone else since that target may not be there at the time. I'm talking about the 5 ft step and full attack versus a move and cast a spell.
The only time you generate an AoO when casting a spell is hen actually casting it - not the entire round (which is another extrapolation of the continutiy issue).