  Heavy long-lived quarks, i.e. charm and bottom, are frequently studied both
as tests of QCD and as probes for other physics aspects within and beyond the
standard model. The long life-time implies that charm and bottom hadrons are
formed and observed. This hadronization process cannot be studied in isolation,
but depends on the production environment. Within the framework of the string
model, a major effect is the drag from the other end of the string that the c/b
quark belongs to. In extreme cases, a small-mass string can collapse to a
single hadron, thereby giving a non-universal flavour composition to the
produced hadrons. We here develop and present a detailed model for the
charm/bottom hadronization process, involving the various aspects of string
fragmentation and collapse, and put it in the context of several heavy-flavour
production sources. Applications are presented from fixed-target to LHC
energies.
