Permissible : (As applied to any device, equipment or appliance)- such device, equipment or appliance has the formal approval of the United States Bureau of Mines, American Standards Association, or National Board of Fire Underwriters
US Department of Labor, Logging eTool: Glossary, Occupational Safety & Health Administration OSHA, Washington, D.C., USA 2010. https://www.osha.gov/SLTC/etools/logging/glossary. html, (OSHA/ Logging - Amer) {620}