Purchasing uses a comprehensive defaulting mechanism to provide most required purchase order information and minimize document creation time. For example, when you are entering a standard purchase order and you want only one shipment and distribution for each purchase order line, you do not need to navigate beyond the Lines tabbed region unless you want to change the default information in the shipments and distributions that Purchasing automatically creates.

Note that the Account Generator may be unable to build accounts for a number of reasons related to defaults. For example, if you have entered a one-time item and there is no default account for your user or category. In this case, you must enter distributions in the Distributions window.

Item revision : The latest Item revision does not default onto a requisition or  purchase order for an inventory item that is revision controlled. This is currently standard functionality to not default a revision at the  requisition line level.  The same is true at the PO line level also.  The only  place we default the revision is on the receipt.  At time of receipt we do  default the latest revision although we allow the user to override the revision  with any valid revision.