frame-index marker

(35 mm only) Hyphen that occurs every four perforations to help locate position of frame line, especially in low-light level scenes. To use: Locate frame line. Determine whether it is offset from index marker by 0, +1, +2, or +3 perforations. Use this offset to find frame line elsewhere in scene. Note: The frame-index marker is not printed when it interferes with any other edgeprint information.