Operators and predicates
Part of the need for something like REC comes from the proliferation of options in a program, and in finding some way to deal with them. As written, most programs already contain options to perform the simple and basic actions. To combine them requires careful attention from the keyboard; so REC serves pretty much in the role of a universal macro implementation. It contains all the control structure which is required, wherein the previously existing options can serve as the operators. Predicates must be introduced; these can take the form of counters, responses to pressing a key, or some internal condition within the program such as a vanishing field.
Harold V. McIntosh