This paper presents a mathematical representation of the three dimensional tolerance zones defined in the ANSI Y14.5 M standard. The tolerance zone models are based on the small displacement screw which is a screw parameter expressing first order approximation of traditional homogeneous transformation matrix. Modeling of datum system and complex surface association is also taken into account as well as modeling of multiple tolerance specifications and material modifiers. Application of the representation model is presented on a simple tolerance transfer case where emphasis is put on the translation components of the tolerance zones. The screw parameter representation is also compatible with the Technologically and Topologically Related Surfaces (TTRS) representation model.