  We establish a connection between the distribution functions of quarks in
spin-one hadrons and the helicity matrix for forward scattering of antiquarks
off spin-one hadrons. From positivity of this matrix we obtain inequality
relations among the distribution functions. Analogous relations hold also for
fragmentation functions. The bounds we obtained can be used to constrain
estimates of unknown functions, occurring in particular in semi-inclusive deep
inelastic scattering or e+ e- annihilation with vector mesons in the final
state.
