用例使用圆括号()包裹，也可以使用关键字usecase来定义用例，还可以用关键字as来定义Alias，这个Alias可以在以后定义关系的时候使用。
@startuml
(First Usecase)
(Another Usecase) as (case2)
usecase case3
usecase (Last\nNewCase) as case4
@enduml
First Usecase Another Usecase case3 Last NewCase
用例描述若是要跨越多行，可以用双引号包裹，还可以使用分隔符：
代码 描述
–横线
..虚线
==双横线
__下划线
@startuml
usecase UC1 as "You can use
several lines to define your usecase.
You can also use separators.
--
Several separators are possible.
==
And you can add titles:
..Conclusion..
This allows large description."
@enduml
You can use several lines to define your usecase. You can also use separators. Several separators are possible. And you can add titles: This allows large description. Conclusion
角色使用两个冒号:包裹，也可以使用关键字actor来定义，同样地，也可以使用as来定义Alias。
@startuml
:First Actor:
:Another\nActor: as Man2
actor Woman3
actor :Last Actor: as Person1
@enduml
First Actor Another Actor Woman3 Last Actor
角色的外观默认为火柴棍人，但是也可以更改成用户头像 样式或者透明人 样式：
@startuml
:Default:
@enduml
@startuml
skinparam actorStyle awesome
:UserAvatar:
@enduml
@startuml
skinparam actorStyle Hollow
:Hollow:
@enduml
Ian Goo