  We review the status of the calculation of the time-like splitting functions
for the evolution of fragmentation functions to the next-to-next-to-leading
order in perturbative QCD. By employing relations between space-like and
time-like deep-inelastic processes, all quark-quark and the gluon-gluon
time-like splitting functions have been obtained to three loops. The
corresponding quantities for the quark-gluon and gluon-quark splitting at this
order are presently still unknown except for their second Mellin moments.
