Purchase Order 
Definition
A request or instruction from a purchasing organization to a vendor (external supplier) or a plant to deliver a quantity of material or to perform services at a certain point in time.
Use
EAN.UCC/GS1 Compliance adds the following new features to the existing mySAP ERP processes:
Input help in the interface enables a material number to be determined from a Global Trade Item Number (GTIN), and from additional information.
In the IDocs, a material number is determined from a GTIN and from additional information, using determination logic.
This enables the material-related processes to be carried out in the same way as before.
Structure
A purchase order comprises a document header and items.
The information contained in the header applies to the entire purchase order. The document header might contain the terms of payment and delivery, for example.
A procurement type is determined for each item. The following procurement types exist:
Standard
Subcontracting
Consignment
Stock transfer
Service
The total quantity of materials to be delivered or services to be performed (defined in the purchase order item) can be subdivided in the schedule lines into various partial quantities with the relevant delivery dates.
For purchase order items that are subcontracted, the material components to be provided can be specified for each delivery date.
An item of the service procurement type contains service specifications. Outline levels structure the service specifications and service lines determine the quantity ordered. For services that cannot be specified precisely, value limits are provided instead of service lines.
When services are called up from contracts, the purchase order item can contain a value limit with reference to a particular contract.
Integration
If you have maintained the vendor-specific GTIN table, you can use it as the first source of supply in the GTIN determination for the purchase order.