On an entity you can set a validationrule. When the rule fails a static text gets shown. I want more options for making the message more descriptive. For starters the value of the attribute that is tested, even better would be the attribute's entire object. In fact, I want it to be as powerfull as the microflows created all over (BCo_<Entity>_Validationetc..).
+1 for this. The static texts should be retrievable from a constant or enumeration, and furthermore it should be possible to execute arbitrary business rules in order to validate an attribute.