SMPTE 195-2000

This standard specifies the maximum dimensions of the film image area intended for projection from a 35-mm motion-picture film and the placement of this area relative to the perforations and the reference edge of the film.This standard specifies three types of image areas intended for theatrical projection.
Style A: General theatrical release prints commonly referred to as nonanamorphic or wide screen;
Style B: Theatrical release prints with an anamorphic image;
Style C: Classic theatrical prints.