ESDU 76016 describes a generalised method for representing a smooth stress/strain curve by an equation involving Young's modulus@ a reference stress and a characteristic index. The determination of those last two quantities is explained. The method is valid for tension or compression and provides a convenient method for accounting for the behaviour of a material beyond its elastic range@ for example in buckling calculations. The method allows simple calculation of tangent and secant modulus and Poisson's ratio but calculation of stress at a given strain or at a ratio of stress to tangent modulus is less easy. For that case approximate equations are given or an exact solution may be obtained using the Fortran program provided as ESDUpac A7616. Tables list the two constants that define the compressive stress/strain curve for 29 aircraft specification materials.