Final answer:
White placards with black stripes represent non-flammable gases in the context of hazardous materials transportation, and these materials need to be handled according to strict regulations.
Step-by-step explanation:
White placards with black stripes typically indicate non-flammable gases in the context of hazardous materials transportation. This classification encompasses materials that may not be flammable, but can still pose a hazard due to pressure or other chemical properties. It is critical to handle these materials with caution, following regulations set by the United States Department of Transportation and the Environmental Protection Agency.