Electrical Code…
Recognized as suitable for the specific purpose, function, use, environment, application, and so forth, where described in a particular Code (NEC) requirement.
Informational Note: Some examples of ways to determine suitability of equipment for a specific purpose, environment, or application include investigations by a qualified testing laboratory (listing and labeling), an inspection agency, or other organizations concerned with product evaluation.
(National Electrical Code® 100-1)