It is shown that the D--meson, whose light quark is the initial-pion valence
quark and whose charmed quark is produced in annihilation of valence quarks and
has got a large enough momentum, is really a leading meson in reactions like
π−p−>DX. If such annihilation of valence quarks from initial hadrons is
impossible there must be no distinct leading effect.Comment: 4 pages, 2.ps-figure