HitPolicy UNIQUE violated

Given the decision table below, I don’t understand how I get a FlowableException with Cause: HitPolicy UNIQUE violated. How should I interpret the dash symbol ‘-’ ? Isn’t it equal to anything not defined in another rule?

The - matches anything, regardless of whether it was used before or not. If you want to use Unique, you’ll need to add rules every possible outcome, which might not be a bad thing if your environment requires you to be that explicit. If you don’t want to have 8 rows with 7 of them having the same output, your best bet for this situation is probably using either First or Priority.