The simple models of shelf circulation components discussed so far were based on the coastal constraint assumption and longshore uniformity. This is clearly restrictive: how far from shore the coastal constraint is valid is itself one of the important questions in shelf dynamics. A longshore sea-level gradient constant in space and time is evidently not a realistic assumption over larger pieces of the coastline. The focus of much recent work on shelf dynamics has been on determining the mechanism that allows longshore sea-level gradients to exist along open shelves, and the distribution of such gradients. The excitement of finding answers to such questions is still fresh for those of us involved in the exercise.