Purchase order processing UML activity diagram

This purchase order processing UML activity diagram was created on the base of activity diagram from the software architecture documentation wiki of the Software Engineering Institute (SEI) of Carnegie Mellon University (CMU).
[wiki.sei.cmu.edu/ sad/ index.php/ Image:PurchaseOrderActivityDiagram.png]
"A purchase order (PO) is a commercial document and first official offer issued by a buyer to a seller, indicating types, quantities, and agreed prices for products or services. Acceptance of a purchase order by a seller forms a contract between the buyer and seller, so no contract exists until the purchase order is accepted. It is used to control the purchasing of products and services from external suppliers.
Creating a purchase order is typically the first step of the purchase to pay process in an ERP system." [Purchase order. Wikipedia]
This purchase order processing UML activity diagram example was created using the ConceptDraw PRO diagramming and vector drawing software extended with the ATM UML Diagrams solution from the Software Development area of ConceptDraw Solution Park.

"A broker is an individual or party (brokerage firm) that arranges transactions between a buyer and a seller for a commission when the deal is executed. A broker who also acts as a seller or as a buyer becomes a principal party to the deal. Distinguish agent - one who acts on behalf of a principal. ...
In general a broker is an independent agent used extensively in some industries. A broker's prime responsibility is to bring sellers and buyers together and thus a broker is the third-person facilitator between a buyer and a seller. An example would be a real estate broker who facilitates the sale of a property.
Brokers also can furnish market information regarding prices, products, and market conditions. Brokers may represent either the seller (90% of the time) or the buyer (10%) but not both at the same time. An example would be a stockbroker, who makes the sale or purchase of securities on behalf of his client. Brokers play a huge role in the sale of stocks, bonds, and other financial services." [Broker. Wikipedia]
The UML composite structure diagram example "Sale process" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Rapid UML solution from the Software Development area of ConceptDraw Solution Park.