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223 Hazardous Materials Warning Labels and Markings

Most mailable hazardous materials fall in the ORM-D (other regulated materials), consumer commodity, or mailable limited quantity categories. ORM-D materials (surface only) may include an ORM-D marking or a Department of Transportation (DOT) square-on-point marking. Most materials intended for air transportation must bear a DOT square-on-point marking, including the symbol “Y”, and may require a specific DOT diamond–shaped hazardous materials warning label and other markings. See chapter 3, Exhibit 325a, Exhibit 325b, and DMM 601.10 for more specific information on hazardous materials warning labels and marking requirements.