B-pillar
B-pillar means the forwardmost pillar on each side of the vehicle that is, in whole or in part, rearward of a transverse vertical plane passing through the seating reference point of the driver's designated seating position or, if there is no driver's designated seating position, the forwardmost pillar on each side of the vehicle that is, in whole or in part, rearward of a transverse vertical plane passing through the seating reference point of the rearmost designated seating position in the front row of seats, unless:
(1) There is only one pillar rearward of that plane and it is also a rearmost pillar; or
(2) There is a door frame rearward of the A-pillar and forward of any other pillar or rearmost pillar.