His full term is "representations of design", and he uses it previously in the following ways: Languages aren’t design; they’re representations for writing dow

His full term is "representations of design", and he uses it previously in the following ways: Languages aren’t design; they’re representations for writing down the design once we get it. Quit thinking of external representations as what design is all about, and focus on mental process. By representations of design, he means something more concrete and less fluid than mental models. Even mathematical notation is less fluid than mental models, because they presuppose the terms of reference, which is a solidification of a model, which makes it harder to even visualize the problem in other terms. BTW: lisp is more fluid than java, but less fluid than mental models.