1. A printed document including a data structure encoded on a surface of at least one page of the document, said data structure comprising a plurality of block data regions, each of said block data regions including: an encoded data region containing data in encoded form; a plurality of clock mark structures located on mutually opposite sides of said encoded data region; and a target structure located adjacent said clock mark structure; wherein each of said block data regions further includes an orientation data structure indicative of an orientation of said data structure.