What is the difference? âââââââââââââââââââââââââââââââââââââ *ShouldBeImplemented* I am ShouldBeImplemented, an exception signaled when some method should have been implemented but was not. This is more like a placeholder during development. âââââââââââââââââââââââââââââââââââââ *NotYetImplemented* I am NotYetImplement, an exception signaled when a method is a stub for code that will be implemented in the future. This is used in incremental development, for example when doing Test First development. It is similar to ShouldBeImplemented, with a slightly different meaning. âââââââââââââââââââââââââââââââââââââ There seem to be some slight semantic difference but I'm failing to see it. I can even say "The method should be implemented, but is not yet implemented." It's saying the same thing with different words. Thanks, Peter