  We calculate $p, \pi^\pm, K^\pm$ and $\Lambda$(+$\Sigma^0$) rapidity
distributions and compare to experimental data from SIS to SPS energies within
the UrQMD and HSD transport approaches that are both based on string, quark,
diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom. The
two transport models do not include any explicit phase transition to a
quark-gluon plasma (QGP). It is found that both approaches agree rather well
with each other and with the experimental rapidity distributions for protons,
$\Lambda$'s, $\pi^\pm$ and $K^\pm$. Inspite of this apparent agreement both
transport models fail to reproduce the maximum in the excitation function for
the ratio $K^+/\pi^+$ found experimentally between 11 and 40 A$\cdot$GeV. A
comparison to the various experimental data shows that this 'failure' is
dominantly due to an insufficient description of pion rapidity distributions
rather than missing 'strangeness'. The modest differences in the transport
model results -- on the other hand -- can be attributed to different
implementations of string formation and fragmentation, that are not
sufficiently controlled by experimental data for the 'elementary' reactions in
vacuum.
