Patent ID: 7352379

Claim:
A sheet for forming an image comprising a substrate film and two or more image-formative layers disposed thereon, the image-formative layers being defined by frame respectively and arranged in a longitudinal direction of the substrate film, wherein an identifying mark comprising a sequence of mark bits which records information concerning the sheet for forming an image is provided to the sheet for forming an image in a manner of allocating respective mark bits to unit frames each of which comprises a single frame or plural frames of the image-formative layer with the mark bits being arranged in order of the sequence recording the information with at least one cycle period comprising a certain number of the unit frames along with a longitudinal direction of the sheet for forming an image, and wherein the sequence of the mark bits constituting the identifying mark is a combination of a sequence of mark bits constituting a first mark A with a sequence of mark bits constituting a second mark B, the first mark A having a cycle period of a natural number X, the second mark B having a cycle period of a natural number Y different from said X and relatively prime with said X, and the first mark A and the second mark B being different from each other.