Configure, price, quote (CPQ) software helps sellers quote complex and configurable products.[1] An example could be a maker of heavy trucks. If the customer chooses a certain chassis (the base frame of a motor vehicle), the choice of engines may be limited, because certain engines might not fit a certain chassis. Given a certain choice of engine, the choice of trailer may be limited (e.g. a heavy trailer requires a stronger engine), and so on. If the product is highly configurable, the user may face combinatorial explosion, which means the rapid growth of the complexity of a problem. Thus a configuration engine is employed to alleviate this problem.