Please mind the formatting of your posts, and the usage of 'backticks' - see the top of the page. This way your code will be much more readable. Also, there is a preview pane that shows exactly how the post will be visible to others.

@backtrader My goal is described in my old post: https://community.backtrader.com/topic/1076/daily-upper-and-lower-bound-of-price/3 Only here I am trying to take into account daily upper and lower bound of price for target order. target order or not, I did try to follow your suggestion in old post, but: Having a custom Sizer This wont work for me since my order are with specific size, a global custom Sizer will be overwritten. 2.Having a commission scheme I read the custom commission scheme, dont see how this will work. The def _getcommission(self, size, price, pseudoexec) only pass in the execution price for orders, not previous bar's (when the order is created) close price, I wont be able to compare these two prices thus impose an inf commission accordingly. Official name for such trading restriction is called daily maximum price fluctuation I think, and it is common in commodity futures as well, might be a good idea to implement such feature natively.