Underwriters Laboratories (UL) 

UL Directories contain listings of the products that have been currently tested by UL for conformance with industry standards and UL standards. When U.S. building codes call for independent testing or approval, most code authorities accept UL-listed products. There are 10 directories of interest, each published once a year.

Of the U.S. independent testing agencies for construction products, UL has the widest coverage of product types. UL tests products to UL standards in most cases. Many UL standards have equivalents published by other organizations, including ASTM and NFPA, but others are exclusive to UL. UL standards are not included in the directories and must be purchased separately; ask for the Catalog of Standards.

SpecLink does not reference the UL Directories themselves, but instead offers the option of requiring products to be UL Listed or Labelled, as appropriate.