This European Standard specifies a test method for determining the mechanical viscoelastic properties of interlayer materials. The interlayers under examination are those used in the production of laminated glass and/or laminated safety glass. The interlayer properties are needed in order to determine the load resistance of laminated glass in accordance with prEN 16612:2017 [1]. From the tensile modulus in particular conditions of temperature and load duration, an interlayer can be placed into a family that relates to a specific interlayer shear transfer coefficient, É. This value can be used in the simplified calculation method described in prEN 16612:2017 [1]. An informative annex explains the background to the determination of families relating to a specific interlayer shear transfer coefficient.