  The recently submitted preprint on the first results from the XENON100 dark
matter experiment (arxiv:1005.0380) was followed by a criticism by J.I. Collar
and D.N. McKinsey (arxiv:1005.0838), focused on our extrapolation of the
scintillation efficiency L_eff to the lowest nuclear recoil energies, where no
data and no theoretical model exist. Here we add clarifications on our analysis
and comment on their criticism.
