  We investigate charm production in charged-current deep-inelastic scattering
(DIS) using the xFitter program. xFitter is an open-source software framework
for the determination of PDFs and the analysis of QCD physics, and has been
used for a variety of LHC studies. The study of charged current DIS charm
production provides an important perspective on the strange quark PDF, s(x). We
make use of the xFitter tools to study the present s(x) constraints, and then
use LHeC pseudodata to infer how these might improve. Furthermore, as xFitter
implements both Fixed Flavor and Variable Flavor number schemes, we can examine
the impact of these different theoretical choices; this highlights some
interesting aspects of multi-scale calculations. This study provides a
practical illustration of the many features of xFitter.
