CinemaScope.

In the 1950's Cinemascope, the wide screen format was first printed on 35mm film with small square perforations designed to allow more width of the film to be used for the optically "squeezed" anamorphic picture. These were also known as Fox Hole's [after 20th Century Fox the instigator of the system. CS Cinemascope perforations are not used today. The pitch was a single standard or long pitch of 4.75 mm and designated as CS-4750.