Notification Events: Trigger for something, that is NOT set

[shostakovich]

Once again I run into this problem:

I use the MasterSlave module with OTRS 3. It uses TicketFreeText12. TicketFreeText16Key/Value is "Master/Master", "Slave/Slave" or "/-"

Now I want to send different customer notifications:
- Notification1 if FreeText12 is Master OR empty
- Notification2 if FreeText12 is Slave

I cannot set Notification1 with Action=AdminNotificationEvent because you can not trigger for the empty/not set FreeText12. FreeText12 has the key/value combo ""/"-", but if I select"-" in the AdminNotificationEvent it becomes unselected...

Maybe I'm overseeing something. What's the solution for this? If a negation existed, I'd also use it: Slave/ not Slave...

TIA
Michael