  We discuss limiting fragmentation within a few currently popular
phenomenological models. We show that popular Glauber-inspired models of
particle production in heavy ion collisions, such as the two-component model,
generally fail to reproduce limiting fragmentation when all energies and system
sizes experimentally available are considered. This is due to the
energy-dependence of number of participants and number of collisions. We
quantify this violation in terms of the model parameters. We also make the same
calculation within a Color Glass Condensate scenario and show that the
dependence of the saturation scale on the number of participants generally
leads to violation of limiting fragmentation. We further argue that wounded
parton models, provided the nucleon size and parton density vary predominantly
with Bjorken $x$, could in principle reproduce both multiplicity dependence
with energy and limiting fragmentation. We suggest, therefore, that an
experimental measurement of deviation from limiting fragmentation in heavy ion
collisions, for different system sizes and including the experimentally
available range of energies, is a powerful test of initial state models.
