UML use case diagram - System of goods selling via catalogues

"A catalog merchant (catalogue merchant in British and Canadian English) is a form of retailing. The typical merchant sells a wide variety of household and personal products, with many emphasizing jewelry. Unlike a self-serve retail store, most of the items are not displayed; customers select the products from printed catalogs in the store and fill out an order form. The order is brought to the sales counter, where a clerk retrieves the items from the warehouse area to a payment and checkout station. ...
The catalog merchant has generally lower prices than other retailers and lower overhead expenses due to the smaller size of store and lack of large showroom space.
There are a few key benefits to this approach. By operating as an in-store catalog sales center, it could be exempt from the "Resale price maintenance" policy of the manufacturers, which can force conventional retailers to charge a minimum sales price to prevent price-cutting competition; it also reduces the risk of merchandise theft, known in the industry as shrinkage.
From the consumer's point of view, there are potential advantages and disadvantages. The catalog showroom approach allows customers to shop without having to carry their purchases throughout the store as they shop. Possible downsides include that customers may be required to give their contact information when an order is placed, take the time to fill out order forms, and wait a period of time for their order to be available for purchase. This wait may be days long, one of the chief vulnerabilities of the catalog showroom approach." [Catalog merchant. Wikipedia]
The UML use case diagram example "System of goods selling via catalogues" 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.

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.