BODY IN WHITE - BIW
That stage in automotive design or automobile manufacturing in which the car body sheet metal components are assembled by any means like welding, riveting or bolting, etc. is called BIW (Body In White). Moving parts such as Door, Hood, Trunk Lid, Front Fender, and the components (chassis, motor) and trim (windshields, seats, upholstery, electronics, etc.) are added in a later stage.
X = Longitudinal Direction (For & After) : F/A
Y = Transverse Direction (Center O line): C/C
Z= Vertical Direction(Up & Down): U/D
Front center of a vehicle is defined as the origin of the car body, which is indicated as 0,0,0
BIW includes following parts :
UNDER BODY :
Underbody is the base of BIW, it consists of sub-assembly of the engine room, rear floor, and chassis.
UPPER BODY :
The upper body is the composition of Body Side L/R, Roof Panel, Cowl & Dash, front fender, rear fender, all pillars.
MAIN BODY :
The main body is the assembly of the Under Body and Upper Body.
CLOSURES :
All Doors, Bonnet(Hood), Deck lids are called closures.