Yellow bordered pages in the ERG are used to look up which identifying feature on a placard?

• A. The Hazmat Material Class
• B. The Four digit UN Number
• C. The Packing Group
• D. The Emergency Response Guide's Title

Answer: (B)

Yellow bordered pages are organized to be used with the four-digit UN numbers that appear on hazmat placards. When a responder sees a placard, they look up that UN number in the yellow pages to identify the specific material and access the corresponding safety information and initial response guidance. The UN number uniquely identifies the substance, making it the quickest way to match a placard to the correct entry in the ERG. Other placard details like the hazard class or packing group are relevant, but the yellow pages are specifically keyed by the UN number, not by the title of the ERG.