  Fitting $Z^0$-pole data from ALEPH and SLD, and TPC data at a lower c.m.s.\
energy, we fix the boundary condition for NLO parton$\to$hadron
(hadron$=\pi^\pm, K^\pm, \sum_h h^\pm$) fragmentation functions (FFs) at the
low resolution scale of the radiative parton model of Gl\"{u}ck, Reya and Vogt
(GRV). Perturbative LO$\leftrightarrow$NLO stability is investigated. The
emphasis of the fit is on information on the fragmentation process for
individual light ($u,d,s$) and heavy ($c,b$) quark flavours where we comment on
the factorization scheme for heavy quarks in $e^+e^-$ annihilations as compared
to deep inelastic production. Inasmuch as the light quark input parameters are
not yet completely pinned down by measurements we assume power laws to
implement a physical hierarchy among the FFs respecting valence enhancement and
strangeness suppression both of which are manifest from recent leading particle
measurements. Through the second Mellin moments of the input functions we
discuss the energy-momentum sum rule for massless FFs. We discuss our results
in comparison to previous fits and recent 3-jet measurements and formulate
present uncertainties in our knowledge of the individual FFs.
