Suggestion:
In Sale order, The rate is at which item is sold. This rate is applicable only if the price list is ‘list’ type. For batch type price is picked up only after allocation of stock to the order. The price list is applicable to customers selected in Sales order. It depends on the price list date, it is the date as of which the price to be applied. This is important for the price list of ‘list’ type, which changes over a period. This is not useful for batch price, where the price is linked to a batch of Inventory.