IT and software
Use case diagram (online shop, UML)
A UML use case diagram with the actors, the use cases, and the include and extend relationships between them
This drawing comes from one YAML file. No shape was moved by hand.
Notes in the source (in Japanese)
ユースケース図の主役は、箱ではなく「システム境界」。境界の内側がこれから作るもの、外側がアクター（人と外部システム）。決済代行が外側にあることが、この図がいちばん言いたいこと。
決済代行のような外部システムもアクター。境界の外にあるものは、自分では直せない。 そこを見せるための図。
「支払う」は書くが、「クレジットカード番号を検証する」は書かない。手順を書き始めたら、それはアクティビティ図の仕事（見本 49）。
Source (YAML)
examples/gallery/48-ユースケース図.zumen.yaml
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