To establish Standards, UL works with industry advisory councils for each product category. Sometimes Standards change, and products that at one time met the Standards have to meet new requirements. In that case, UL reviews all products in its massive files and sends a bulletin to all manufacturers alerting them to the revised requirements as well as their effective dates. UL has international arrangements. UL has subsidiary laboratories in Hong Kong and Taiwan, and they offer a service to all manufacturers to advise of the standards in any country.
Safety is a concern worldwide.