olemus
UML:
sihtsüsteemi käitumise väljastvaadet kirjeldav skeem, mis näitab kasutusmallide sidemeid tegijatega
= a graphical depiction of a user's possible interactions with a system

ülevaateid
https://en.wikipedia.org/wiki/Use_case_diagram
https://www.lucidchart.com/pages/uml-use-case-diagram
https://www.andrew.cmu.edu/course/90-754/umlucdfaq.html
https://medium.com/thousand-words-by-creately/here-are-the-use-case-diagram-guidelines-you-need-to-know-d71f79238c78
https://venngage.com/blog/use-case-diagram/

näiteid
http://www.uml-diagrams.org/use-case-diagrams/use-case-diagram-elements.png
https://duckduckgo.com/?t=h_&q=%22use+case+diagram%22&iax=images&ia=images