Heavy Quarks and Structure Functions

I present a method for calculating heavy quark production which extrapolates smoothly from the well understood limits of the fixed-flavour number scheme for Q^2 approx m_H^2 to the zero-mass scheme at Q^2/m_H^2 -> infinity. For all Q^2

m_H^2 the evolution of the heavy quark distribution is precisely as in the massless MSbar scheme. The method is simple to implement and compares well with data.