F.1.12 Major Structure
The portion of the Chassis that lies inside the Primary Structure Envelope, excluding the Main Hoop Bracing and the portion of the Main Hoop above a horizontal plane located at the top of the Upper Side Impact Member or top of the Side Impact Zone.
Explanation
The Major Structure is similar to the Primary Structure, the Major Structure just excludes the part of the Main Hoop above the Upper Side Impact Members. This also excludes the Main Hoop Braces.