Compatibility Group Letter [Transportation] Law and Legal Definition

According to 49 CFR 171.8 [Title 49 – Transportation; Subtitle B -- Other Regulations Relating to Transportation; Chapter I -- Pipeline and Hazardous Materials Safety Administration, Department of Transportation; Subchapter C -- Hazardous Materials Regulations; Part 171 -- General Information, Regulations, and Definitions; Subpart A -- Applicability, General Requirements, and North American Shipments], compatibility group letter means “a designated alphabetical letter used to categorize different types of explosive substances and articles for purposes of stowage and segregation.”