Melt spinning is a prototypical example of many polymer processes: The polymer melt is first subjected to simple shear flow which is followed by uniaxial extension under constant force. The analysis of this complicated deformation history is simplified by the existence of Rheotens super- and grand-mastercurves, These allow a direct and straightforward description of material behaviour in the fibre spinning process, and a simplified determination of an effective elongational viscosity under the action of a constant draw-down force.