Abstract.The element yield distributions a(Z) of intermediate mass fragments from proton, helium, and heavy-ion induced reactions exhibit a universal behaviour as a function of the bombarding energy. The power law parameter ~, obtained from fits with a(Z)ocZ ~, falls monotonically with increasing projectile energy Ela b and reaches a saturation value ~-2.0 at Elab---2 GeV. It is suggested that the behaviour at low bombarding energies is caused by a dynamical hindrance of the fragment emission at low angular momentum. PACS: 25.40.Sc; 25.70.Gh; 25.70.Lm; 25.70.Mn; 25.70.Pq reactions on heavy targets. Our intention hereby is twofold. We first show that the r parameters describing inclusive cross sections exhibit a universal behaviour when plotted as a function of the total projectile energy. They decrease monotonically with increasing projectile energy until they assume a saturation value at several GeV and higher energies. We then search for possible explanations of this behaviour but limit ourselves to the lower bombarding energies. We recall experimental evidence for dynamic effect of angular momentum in fragment emission, and we show that the rise of z towards low bombarding energies may result from a dynamical hindrance of fragment emission at low angular momentum.