2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/185409Where appropriate, the abbreviation 'VFNS' is replaced by 'CSN' to indicate the scheme using massive heavy quark coefficient functions proposed in this paper. The text below Eq. (2.13) and between Eqs. (2.33) and (2.36) has been considerably changed.64 pages, LaTeX, 16 Postscript figuresHigh Energy Physics - Phenomenologytext