was considerably less accurate than BH perfs, which remains the standard for negatives. The KS1870 perforation, or KS perforation with a pitch of , is the modern standard for release prints. These two perforations have remained by far the most commonly used ones. BH perforations are also known as N (negative) and KS as P (positive). The Bell & Howell perf remains the standard for camera negative films because of its perforation dimensions in comparison to most printers, thus it can keep a steady image compared to other perforations. DH perforations The Dubray–Howell (DH) perforation was first proposed in 1932 to replace the two perfs with a single hybrid. The proposed standard was, like KS, rectangular with rounded corners and a width of , and, like BH, was tall. This gave it longer projection life but also improved registration. One of its primary applications was usage in Technicolor's dye imbibition printing (dye transfer). The DH perf never had broad uptake, and Kodak's introduction of monopack Eastmancolor film in the 1950s reduced the demand for dye transfer, although the DH perforation persists in special application intermediate films. CS perforations In 1953, the introduction of CinemaScope by Fox Studios required the creation of a different shape of perforation which was nearly square and smaller to provide space for four magnetic sound stripes for stereophonic and surround sound. These perforations are commonly referred to as CinemaScope (CS) or "Fox hole" perfs. Their dimensions are in width by in height. Due to the size difference, CS perfed film cannot be run through a projector with standard KS sprocket teeth, but KS prints can be run on sprockets with CS teeth. Shrunken film with KS prints that would normally be damaged in a projector with KS sprockets may sometimes be run far more gently through a projector with CS sprockets because of the smaller size of the teeth. Magnetic striped 35 mm film became obsolete in the 1980s after the advent of Dolby Stereo, as a result film with CS perfs is no longer manufactured. During continuous contact printing, the raw stock and the negative are placed next to one another around the sprocket wheel of the printer. The negative, which is the closer of the two to the sprocket wheel (thus creating a slightly shorter path), must have a marginally shorter pitch between perforations (0.1866 in pitch); the raw stock has a long pitch