Hello U.,
Just to answer to an old unanswered question (and confirm that is now OK):
@startuml
Bob -> Alice : hello
Alice -> Charlie: hello
note over Bob, Alice
note over Bob, Alice
end note
hnote over Bob, Alice
hnote over Bob, Alice
end note
rnote over Bob, Alice
rnote over Bob, Alice
end note
@enduml
[See on PlantUML online server]
Regards,
Th.