"This frame element is defined as the number of times an event occurs per some unit of time. A Frequency expression answers the question how often. It is to be distinguished from Iteration, which pertains simply to the number of times an event occurs-Iteration expressions answer the question how many times. In the future, we will further distinguish Particular_iteration, which is intended to pick out a particular iteration from a series. "^^ . "Frequency"^^ . "Extra-Thematic"^^ . . . . . .