UL Subject 991
Standard for Tests for Safety-Related Controls Employing Solid-State Devices (Bulletin, 5/1/2000)
standard by Underwriters Laboratories, 05/01/2000
UL Subject 971
Standard for Nonmetallic Underground Piping for Flammable Liquids (Bulletin, 4/21/2000)
standard by Underwriters Laboratories, 04/21/2000