Please provide an OR logical operator for the ifdef preprocessor command.
Example: !ifdef A || B
(--------)
Hello,
Your proposal is interesting. I do this with a workaround:
@startuml 'define A !define B !ifdef A !define AorB !else !ifdef B !define AorB !endif !endif !ifdef AorB title A or B !endif Bob-> Alice @enduml
http://www.plantuml.com/plantuml/png/Kqn9JSlCIrLmv5A4ifou53FJW6ma8SVy8g1eQavnAapE2LqkBoKp3Kv1zODaIZ9BSe2A5FAB5E3AdFAJTEqK77CoarC1
Hope this helps