We investigate the role of heavy quarks in the production of light flavored hadrons and in the determination of the corresponding nonperturbative hadronization probabilities. We define a general mass variable flavor number scheme for fragmentation functions that accounts for heavy quark mass effects, and perform a global QCD analysis to an up-to-date data set including very precise Belle and BABAR results. We show that the mass dependent picture provides a much more accurate and consistent description of the data.Instituto de Física La PlataConsejo Nacional de Investigaciones Científicas y Técnicas