22 CFR § 120.42 - Form, fit, function, performance capability, equivalent, enumerated, and catch-all control.
(a) Form. The form of a commodity is defined by its configuration (including the geometrically measured configuration), material, and material properties that uniquely characterize it. For software, the form means the design, logic flow, and algorithms.
(b) Fit. The fit of a commodity is defined by its ability to physically interface or connect with or become an integral part of another commodity. For software, the fit is defined by its ability to interface or connect with a defense article.
(c) Function. The function of a commodity is the action or actions it is designed to perform. For software, the function means the action or actions the software performs directly related to a defense article or as a standalone application.
(d) Performance capability. Performance capability is the measure of a commodity's effectiveness to perform a designated function in a given environment (e.g., measured in terms of speed, durability, reliability, pressure, accuracy, efficiency). For software, performance capability means the measure of the software's effectiveness to perform a designated function.
(e) Equivalent. With respect to a commodity, equivalent means its form has been modified solely for fit purposes.
(f) Enumerated. Enumerated refers to any item designated on the U.S. Munitions List or item on the Commerce Control List and not in a catch-all control.
(g) Catch-all control. A catch-all control is one that does not refer to specific types of parts, components, accessories, or attachments, but rather controls unspecified parts, components, accessories, or attachments only if they were specially designed for an enumerated item.