  We compute the structure functions F2 and FL in the ACOT scheme for heavy
quark production. We use the complete ACOT results to NLO, and make use of the
MSbar massless results at NNLO and N3LO to estimate the higher order
mass-dependent corrections. We show numerically that the dominant heavy quark
mass effects can be taken into account using massless Wilson coefficients
together with an appropriate rescaling prescription. Combining the exact NLO
ACOT scheme with these expressions should provide a good approximation to the
full calculation in the ACOT scheme at NNLO and N3LO.
