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Font
To know fonts available on your system, you may use the following special syntax:
@startuml
listfonts
@enduml
You can also add an optional sentence to be displayed:
@startuml
listfonts 私は申し訳ありません：私は日本語を話さない。
@enduml
Examples
Those fontname can be used in any UML diagrams.
@startuml
skinparam defaultFontName Segoe UI
Room *-- Chair : "1" has "several"
@enduml
@startuml
skinparam defaultFontName VL Gothic
部屋 *-- 椅子 : "1" 持っています "いくつか"
@enduml
You can also change font using skinparam command.