In prepress, a group of properly positioned photographic negatives or positives from which a printing plate will be made by exposing the photosensitive plate to the flat. A flat can consist of the negatives or positives attached to the back of a sheet of goldenrod (called a goldenrod flat), with holes cut only over those areas of negative/positive that correspond to regions denstined for exposure. The flat contains all the page elements in the proper position for exposing a plate. (See Stipping.)
In printing, the term flat is also used to refer to a set of pages that are in the proper imposition for folding a signature.