For a V-0 rating, the material must stop burning within 10 seconds after the ignition source is removed.
Because circuit board raw materials are fabricated by hundreds of independent manufacturing plants worldwide, UL requires factories to stamp their unique identifier alongside the safety rating. "SH1" usually points to a specific factory line or a raw laminate supplier (such as Sheng Yi Electronics or similar board manufacturers). Technical Specifications of a 94V-0 Rated Board
Many international markets require UL 94V-0 certification for electronic products to ensure they meet safety regulations.