We present a systematic QCD analysis of the strange--charm and bottom--top
contributions to transverse and longitudinal structure functions in
charged--current deep inelastic scattering. Various O(αs1)
schemes are studied and compared. The dependence of their predictions on the
factorization scale μ2 is investigated. The theoretical uncertainties
resulting from the choice of the scheme and of μ2 are estimated.Comment: 9 page