In supplier definition, user can also attach items to the particular supplier from Supplier-item Pricelist tab. This tab is not visible at the time of new entry and only visible at the time of modification. If items are attached with the supplier then at the time of purchase order, system will show all the items with the price defined in Supplier-Item attachment. If price is not attached with the supplier then the system will pick the Standard Rate for the item defined in item definition during the purchase order entry.
