"Are we talking about a shopping cart with wheels, or one that exists only in an online shopping application? If we're talking about the latter, then we're not talking about modelling the real world, we are talking about designing an electronic virtual world. The two tasks have similarities, but they are not at all the same."

Michael, could you clarify? I am not sure about that difference. At least what concerns the finished model, I cannot see any principal difference between the structures describing, say, a shopping cart, a license, an accommodation, a program, a company, a protein. It is (usually) named items representing concepts, which may in either case have existed before model construction, or are defined in the course of model construction. So perhaps you refer to the design process, rather than to the result, to the effort of "capturing something out there"? A hint would be appreciated.

Hans-Juergen