First, we will describe how some kinds of “cognitive” information can be incorporated into a formal grammar. This information will permit us to describe a system, formally, for different classes of users. Most current models are limited to specific classes of users. They do not, for example, permit us to describe a system differently for naive and for expert users. Next, we will describe, explicitly, the prediction process. The last point to be discussed is our general approach to testing the use of formal grammar as a design tool. This idea is being developed and tested using an IBM editor as an example.