Yes, you are correct. NUnit didn't always recognized derivatives of its attributes because we reflect on the attribute name. However, we started descending the inheritance chain for selected attributes in 2.5 and after a recent bug fix to ExplicitAttribute, I believe all of them are recognized. However, where we expect a single attribute, we use the first one found. AFAIK, there is no way for us to actually enforce use of a single attribute at compile time when inheritance is used, which is clearly a source of confusion. We could introduce a runtime check for those situations where only one such attribute is used. Or we could simply document the problem. Charlie On Tue, Nov 2, 2010 at 1:30 AM, Petr Kuzel