<\body> Functional operators are used for computational purposes during the typesetting phase, such as increasing counters, localizing strings like ``theorem'' and so on. A fundamental set of basic functional operators are built-in primitives. New functional operators can easily be added using the primitive. Functional operators operate on five main types of arguments: strings, numbers, lengths, booleans and tuples. Some operators are overloaded, so that they can be used for several types. <\traverse>