  Recent experimental data on semi-inclusive deep-inelastic scattering from the
HERMES collaboration allow us to discuss for the first time the flavor
dependence of unpolarized transverse-momentum dependent distribution and
fragmentation functions. We find convincing indications that favored
fragmentation functions into pions have smaller average transverse momentum
than unfavored functions and fragmentation functions into kaons. We find weaker
indications of flavor dependence in the distribution functions.
