I know that in "Mage_Sales_Helper_Data" class , there is a field "MAXIMUM_AVAILABLE_NUMBER" in order to control maximum allowed number for order price.
I see the functionality in the cart section in frontend. But I want to have this limit in backend(administration) section. I mean when an admin want to create an order, he shouldn't be allowed to create it if the price is more than a specific amount.
How can I do this? where should I look at?