  We present a new model format for automatized matrix-element generators, the
so- called Universal FeynRules Output (UFO). The format is universal in the
sense that it features compatibility with more than one single generator and is
designed to be flexible, modular and agnostic of any assumption such as the
number of particles or the color and Lorentz structures appearing in the
interaction vertices. Unlike other model formats where text files need to be
parsed, the information on the model is encoded into a Python module that can
easily be linked to other computer codes. We then describe an interface for the
Mathematica package FeynRules that allows for an automatic output of models in
the UFO format.
