Functions are what we define to capture what we want to remember about a concept, and then to make use of that memory to derive information that can be used to our advantage (actually, our enterprise's advantage for the most part). …sounds pretty 'conceptual', I know.

But from a bottom-up perspective, I see concepts realized everywhere in systems. No big shock, really, given the OO nature of CUA interfaces. Going back to my original post, programs like Calculator or Minesweeper are concept-based, in what they do and probably in how they were developed, even without any persistent data kept in a database. So, the need to capture Concepts in a Requirements Tool is reinforced for me, along with the Functions needed to maintain them.