Choice of format (rectangular or otherwise) may be dictated by either job contact or production practicalities or both There are some time –tested formats that have proved to be particularly suited to a wide range of uses. Prints, for example, makes frequent use of the international standard series of A and B paper sizes, which are based on a rectangle having sides in the ratio of the square root of 2. Repeated folding parallel to the short side allows paper in this preparation to be halved into further rectangle – all in the same 1:1.414 proportion – giving the designer a flexible range of proportionally related size with which to work