CPLR meaning in General ?

Pillars are the vertical or nearly vertical supports of a car's window area or greenhouse—designated respectively as the A, B, C or (in larger cars) D-pillar, moving from front to rear, in profile view.

The consistent alphabetical designation of a car's pillars provides a common reference for design discussion and critical communication. As an example, rescue teams employ pillar nomenclature to facilitate communication when cutting wrecked vehicles, as when using the jaws of life.

The B pillars are sometimes referred to as "posts" (two-door or four-door post sedan).