We thank both referees for their helpful comments and detailed reading of the manuscript. Specifically with respect to the points raised by referee 1: 1) gfortran issues ------------------ We have extended the comments on the web page and the README to warn about the possibility of gfortran giving incorrect answers as well as crashing. 2) Mass threshold and schemes ----------------------------- Yes, of course eq.(6) only holds in the MSbar scheme. We've made this clear in the text. We've also made it clear that we have not incorporate mass thresholds in the DIS scheme at NLO, both on p.8 (now -> 9) and p.26 (->28). We've also removed the "nearly always" (residual heavy flavour when crossing a threshold downwards) at the end of section 6.2.1. 3) Typos -------- We've fixed the typos indicated by the referee, together with some other ones that we have since found. We've also taken the opportunity to add some missing reference and clarify one or two points that seemed unclear to us. A full list of changes can be obtained from http://projects.hepforge.org/hoppet/trac/anydiff?new_path=%2Ftrunk%2Fdoc%2FHOPPET-v1-doc.tex&old_path=%2Ftrunk%2Fdoc%2FHOPPET-v1-doc.tex&new_rev=&old_rev=102 4) Sum rules ------------ The absence of tools for determining PDF moments has been rectified with the addition of the TruncatedMoment(...) routine, now described in section 4.4. An EvalPdfTable_Q(...) routine has also been added (described in section 7.2) which returns a PDF object (i.e. a two-dimension array with x and flavour dependence) for a given Q. Together with the TruncatedMoment(...) routine this provides means of accessing the momentum and valence sums when using tabulations. An example of sum rule verification is given also in example_f90/tabulation_example_2.f90 . As concerns automatic verification of sum rules: given the finite range in x, one only has access to truncated moments and these do not satisfy exact sum rules -- to carry out checks on these would involve introducing parameters for tolerances, which would depend on the x-range and on Q. We feel that the complications ensuing from these parameters would outweigh the benefits of automatic checks on sum rules.