The Underwriter Laboratories Inc. (in short UL) is a global independent safety science company founded in Northbrook, USA in the year 1894. They control goods of all kinds that shall be imported into the USA or that are produced in the US of America for example as to the Product Safety. This is done in public interest. When a product or machine is presented to UL for approval, all component parts of the device are examined – e. g. Type Labels as well.
The UL Specification 969 „Standard for Marking & Labeling Systems“ defines the requirements for marking- and labelling-systems with glues, of printed labels, signboards and user guides. Labels are glued by UL onto testing surfaces typical for their application and exposed to typical stresses and strains to reveal evidence about loading capacity and readability. The products get the respective permission/recognition or endorsement as the case may be.