When freight is applied to a purchase order for inventory that freight should only be allocated via the Purchase Order Set module.  The PO Set allocates the freight directly to the item.  The cost of that freight becomes the Delivered Cost and the freight is carried in both the onhand inventory and the associated general ledger inventory for that freight.

It is reduced via Cost of Goods Sold when sales occur.

If this type of non-inventory expense is not created using a PO set the system will not properly have the true COGS.

When a payable with a purchase order is entered the associated General Ledger accounts for the inventory are calculated from the PO Set distribution to keep the General Ledger in balance.

If the associated inventory Purchase Orders have not been received the user will get an error preventing the selection of the PO until the inventory is received.