AONAll or None means exactly what it says........the broker either fills your order completely or not at all. Your example of 30K @ .30 I assume you mean you've placed an order to buy 30K @ .30 and it's a day only order. If the broker can only buy 500 @ .30 and the price takes off, you get none. Same for sales. You put an order in to sell 30K @ .30 and only get filled for 500, you sell none. It's designed to protect us , the investor, against the broker only giving you a partial fill of say 100 @ .30 or a $30 trade and charging you a $30 commission. Then you have to place another order to buy/sell at a different price and he makes another commission. The change is strictly in favor of the broker!
So what's new?