We have tried to be faithful to this model by forcing all operators that are selected in the top space to fit into one of the operator categories outlined by this work. Specifically, there are four kinds of operators, which appear in various ways within our model:
Each of these operators has a specific, reasonably well delineated set of functions, and all operators fall into one of these categories. Because all interaction with the world is being done from the top space, non-contemporaneous chunking and other difficult I/O problems are much more readily avoided.