  We define a new variable flavour number scheme for use in deep inelastic
scattering, motivated by the need to consistently implement high energy
resummations alongside a fixed order QCD expansion. We define the DIS(chi)
scheme at fixed order, and show how to obtain the small x coefficient functions
and heavy flavour matrix elements to leading order in the high energy
resummation. We then implement these results in a global fit at LO which
includes leading resummations with running coupling corrections. Finally, we
address the impact of the resummed results on predictions for the longitudinal
structure function. We find that they stabilise the behaviour of F_L at small
x. Overall, we find that resummations significantly improve the fit to
scattering data in the low x regime, although higher orders in the fixed order
expansion are needed to describe current structure function and related data
over the complete x range.
