Dear Peter, many thanks for the opencharm paper, it is very well-written to present a vast number of important results while staying concise! Below are my comments to paper draft v5.1 (apologies in advance for the lengthy mail and for not having carefully read the previous version). 1) p.1, 1st para, line 7: citation formatting [4]-[9] --> [4-9] 2) p.1, end of 1st para. of subsection 2: citation formatting [16]-[22] --> [16-22] 3) p.2, 1st para: 3a) to me the word "typically" looks a bit confusing, i thought it was just exactly 300 mkm (cathode+anode) everywhere in ITR "__typically__ 300 um pitch" --> "$\sim 300~\mu\mbox{m}$ readout pitch" 3b) there are too many long phrases in parentheses in this paragraph, i'd re-shuffle the parentheses e.g. as follows: --> ... (ITR) --- microstrip gas chambers with gas electron multiplication and $\sim 300~\mu\mbox{m}$ readout pitch~\cite{ITR}, and a coarse grained outer tracker (OTR) --- honeycomb drift cells with 5 mm and 10 mm cell diameters~\cite{OTR}. The momentum resolution can be parameterized as $\sigma_p/p = 1.61+(0.0051\cdot p~[\mbox{GeV}/c])~\%$ \cite{OTR}, where $p$ is the particle momentum. 3c) formatting of the momentum resolution "0.0051pc/GeV)\%" looks awkward, better formatting similar to that of the OTR paper: --> $\sigma_p/p = 1.61+(0.0051\cdot p~[\mbox{GeV}/c])~\%$ 3d) i'd combine the two references to two OTR papers [18] (II) and [19] (III) into one reference and also add their paper number (I) -- see comment (32j) to the list of citations below. (Note, that sigma_p/p refers to the III OTR paper, though probably it's ok to cite the same paper in two consecutive sentences as in (3b) ...) 4) p.2, 3rd paragraph: I think that the complete 3rd paragraph describing ECAL and MUON can be safely dropped out since these subdetectors were not used in the described analysis. Just move corresponding citations of the corresponding detector papers to the 2nd paragraph on page 2. 5) p.2, line 3 of 4th para.: the abbreviation (VDS) has been already defined on p.1, leave either --> "... following components: the vertex detector, the OTR ...", or --> "... following components: the VDS, the OTR ..." 6) p.2, Table 1: the errors on luminosity numbers are missing. Though, in this context that may be ok. The dominant lumi error is the systematical one which is mentioned separately in Table 5 (see the comment (18) on lumi errors to Table 5). 7) p.3, 5th para (left column, line 5 from the bottom of the page): I just wonder whether one needs to mention that $x_F$ is "the Feynman x", or not. At least, in case one needs to, then here is the place where it is first used in "$-0.15 < x_F < 0.005$". 8) p.4, Table 2: 8a) D+ -> K-pi+pi+: cut value "L_K(K) > 0.5" differs both from the analysis Note, Tab 10, and Samo's thesis (Tab 4.2), where it is L_K(K) > 0.33. (The same cut "L_K(K) > 0.5" for D+ is also mentioned in the text on p.3, line 8 of the 2nd para of subsection 3.1) 8b) D+ -> K-pi+pi+: cut values "b(K)b(pi_1)b(pi_2) > 106" and "sqrt[3]{b(K)b(pi_1)b(pi_2)} > 4(t-t_0), \;\; t_0=2.48" differ from the analysis Note, Tab 10 and Samo's thesis (Tab 4.2). 9) p.6, 1st para, line 3: "... to the parameterizations" in some places you write "parameterizations" and in others "parametrizations" afaik, both are correct spellings, but better use one (please search through the text in the editor for other occurrences of these two forms). 10) p.6, Eq. 1: 10a) probably needs a colon before the formula 10b) and needs a comma after the formula 11) p.6, line 12: "and $x_b$ was assumed to be" (the assumed value missing) 12) p.6, last paragraph of subsection 4: "... the same reconstruction codes as that ..." --> "... the same reconstruction codes as those ..." 13) p.6, Eq. 3: "\Delta\sigma_{pA}" --> "\Delta\sigma_{pA,\,i}" 14) p.6: 14a) add dots after the Eqs. 5, 7, 8. 14b) add colons before Eqs. 6, 8. 15) p.6, right column, line ~10: probably the "A" should be in italics "..., a linear A dependence ...": --> "..., a linear $A$ dependence ..." 16) p.6, right column, lines 10-12: a verb seems to be missing "of the production cross section assumed, ..." --> "of the production cross section was assumed, ..." 17) p.6, right column, end of the next-to-last paragraph: I think one should add a comment on how the estimates of the other two systematic errors (track reco and particle identification) were obtained. This is especially important for the PID systematics since the whole analysis heavily relies on the RICH PID. I would add something like: --> "The systematic errors of track reconstruction and RICH particle identification (1.5\% and 2.0% per track correspondingly) were estimated using decays of $K0_S$ and $\phi$ as sources of pions and kaons~\cite{Pernack,Kupper}." Strictly speaking, in the Note and Samo's thesis it's mentioned that a momentum- dependent efficiency correction factor determined from the above PID studies was applied on top of the MC efficiency. I don't know if that deserves to be mentioned in the paper, or if that would already be too much of a technical detail... 18) p.7, Table 5.: Luminosity systematical errors. The lumi errors quoted in Table 5 (3.4%) are the same as in the analysis Note subsection 6.1.3 which seems to be out of date. In Samo's thesis, subsection 7.1.3 the lumi errors correspond to the ones of the lumi paper submitted for publication. The difference between the two is probably negligible, but please check which lumi errors were actually used for the results in the paper. 19) p.7, 3rd paragraph of subsection 5.2: To my view the procedure of simultaneous fit is too complex and there is no or only a little use in describing it without giving much more details (e.g. other background parametrization formulas which were tested, motivations for using the same functional form of background for D0 and D+ (e.g. though in mass the D0 and D+ background differ so much), mentioning that for D*+ not a side-band, but wrong-sign combinations from the signal window, etc.). Note also, that the fit procedure as described now is much more detailed for p_T than for x_F. So I would propose to rephrase the 3rd paragraph giving a reference to Samo's thesis for a more detailed description of the fitting procedure. One can also combine the resulting phrase into the 2nd paragraph: e.g. --> "The likelihood included the paramet?rization given in Eq. 1 to describe the signal events, with $\langle p_T\rangle$ and $\beta$ being common to all $D$ meson species, and a three bell-shaped terms (with their functional form tested in the sideband regions) to account for kinematical distribution of the background separately in each $D$ meson signal channel~\cite{Kupper}." or --> "The likelihood included the paramet?rization given in Eq. 1 to describe the signal events, and three bell-shaped terms to account separately for kinematical distribution of the background in each $D$ meson channel. The parameters $\langle p_T\rangle$ and $\beta$ were common to all the $D$ meson species. The functional forms used to describe the backgrounds had been tested in the sideband regions and both their normalization and shape parameters were allowed to vary independently for each of the $D$ meson signal channels~\cite{Kupper}." 20) p.8, left column, line 11: I think, if the value = 0.9~Gev/c extracted from Pythia MC has any important meaning, then one should mention the version of Pythia (isn't it the default hera-b Pythia 5.7?). 21) p.8, right column, last line: concerning the sigma(D+)/sigma(D0) predicted by Pythia: same as (20), by which version of Pythia, was it additionally tuned, etc.? 22) p.9, left column, line 7: since [5] is NA27, and [9] refers to E769 "... results of E769 and NA27 [5,9]." --> "... results of NA27 and E769 [5,9]." 23) p.9, left column, line 9: "... ways ([1] and references therein) ..." --> "... ways (see [1] and references therein) ..." 24) p.9, right column, line 2: 24a) introduce some symbol for the asymmetry, e.g. \mathcal{A}(D) which can be also used in the header of Table 10 24b) use an \mbox{} in the subscript of non-leading \sigma or write \sigma{non~LP} to avoid that "non" and "LP" fuse together, e.g.: --> "$\mathcal{A} \equiv (\sigma_{\mbox{\scriptsize LP}} -\sigma_{\mbox{\scriptsize non LP}})/(\sigma_{\mbox{\scriptsize LP}} +\sigma_{\mbox{\scriptsize non LP}})$" 25) p.9, right column, lines 10-11: In the erratum to the paper of E769 [9], it is said that the errors on the asymmetries should be increased by factor 2 compared to their paper, --> correct the errors of the E769 asymmetries to: 0.06+-0.13, 0.18+-0.11, and 0.36+-0.26. 26) p.9, Table 10 + right column, lines 10-12: Listing of all the values of asymmetries measured by other experiments in the text makes it more difficult to read. Maybe one could collect them in Table 10, which then also could be referred to as a "comparison" with other experiments? E.g.: --> \begin{table}[h] \caption{Leading to non-leading particle asymmetries $\mathcal{A}$ (defined in the text) in the visible range, compared with asymmetries published by other experiments. The visible range of E769 is $x_F > 0$, and that of E789 is $0 < x_F < 0.08$. \label{label-of-tab-10} } \begin{tabular}{lccc} \hline & $\mathcal{A}(D0)$ & $\mathcal{A}(D^+)$ & $\mathcal{A}(D^{*+})$ \\ \hline HERA-B & $0.10\pm0.09\pm0.05$ & $0.14\pm0.11\pm0.06$ & $0.23\pm0.17\pm0.06$ \\ E769~\cite{E769} & $0.06\pm0.13$ & $0.18\pm0.11$ & $0.36\pm0.26$ \\ E789~\cite{E789} & $0.02\pm0.06$ & --- & --- \\ \hline \end{tabular} \end{table} 27) p.10, Table 11 27a) 1st line of the caption of the Table: "dependency" --> "dependence" 27b) 1st line of the caption of the Table: "... parameter $\alpha$ and a" --> "... parameter $\alpha$ and its" (?) 27c) try if centering of the "$\alpha$" in the header of Table 10 would make look nicer (?) 28) p.10, left column, line 2: please clarify which version of the lumi errors was used. (e.g. in Samo's thesis the lumi numbers correspond to the lumi paper and lead to the typical value of the error on alpha ~2.2%). 29) p.10, left column, line 8 of the Summary: "... were measure: ..." --> "... were measured: ..." 30) p.10, 2nd and 3rd paragraph of the Summary: To my view the summary looks too bulky because of so many values of all the main results. Wouldn't it look nicer just to refer to Tables 6 and 9 (and perhaps also collect the two P_V measurements in Table 9)? 31) p.10, left column, line 8 from bottom: add citation to the PDG: "... from $e^+e^-$ collisions." --> "... from $e^+e^-$ collisions~\cite{PDG}." 32) pp.10,11 (References) 32a) many references lack a comma between the author list and the journal name 32b) all references lack a dot in {\it et al.} 32c) [1] "H.~W\"ohri" --> "H.K.~W\"ohri" 32d) [2] "G.~Ridolfi G" --> "G.~Ridolfi" 32e) [3] NPB327, (1989) 49: there also exists an erratum (some formulas for differential cross section in the limit of high sqrt{s}, p_T >> m_c) --> add "(Erratum-ibid. {\bf B335}, (1990) 260)" 32f) [9] PRL77, (1996) 2388: formatting of the reference to the erratum "(Erratum-ibid. 1998 {\bf 81} 1537)" --> "(Erratum-ibid. {\bf 81}, (1998) 1537.)" 32g) [10] "P.~Nason P" --> "P.~Nason" 32h) [11-14] "I.~Abt (HERA-B Collaboration) {\it et al}" --> "I.~Abt {\it et al.} (HERA-B Collaboration)," 32i) [14]: * extra "2007" after "et al" * "(2006)" --> "(2007)", * "Eur. J. Phys. C" --> "Eur. Phys. J. C"; in total, the Psi' reference should look like: -->"I.~Abt {\it et al.} (HERA-B Collaboration), {\it Eur. Phys. J. C} {\bf 49}, (2007) 545." 32j) [18,19]: (OTR paper, parts II and III) * [19]: "NIMA576, (2007) 313" --> "NIMA576, (2007) 312" * I'd propose to combine the OTR papers under one \bibitem and add there also the 1st part of the OTR trilogy. By the way, yesterday I found that SPIRES knows only about its e-print version, therefore I think it would be good to cite the NIM versions of the complete OTR trilogy. --> \bibitem{OTR} H.~Albrecht {\em et al.,} {\em Nucl. Instrum. Methods A} {\bf 555}, (2005) 310; ibid. {\em A} {\bf 541}, (2005) 610; ibid. {\em A} {\bf 576}, (2007) 312. 32k) [20]: "I.~Ari\~no I" --> "I.~Ari\~no" 32l) [23]: "R.~Battiston R" --> "R.~Battiston" 32m) [24]: * lumi paper is a collaboration one (thus in SPIRES and in the arXiv) * [hep-ex] --> [physics.data-an] "M.~Bruschi {\em et al} arXiv:0706.0131 [hep-ex] (2007)" --> "I.~Abt {\em et al.} (HERA-B Collaboration), arXiv:0706.0131 [physics.data-an] (2007)" 32n) [25] "W.M.~Yao" --> "W.-M.~Yao" 32o) [26] "T.~Sjostrand" --> "T.~Sj\"ostrand" (well, though SPIRES knows him as T.~Sjostrand without umlaut...) 32p) add citations to Robert Pernack's and Samo Kupper's theses (cf. comments (17, 19)): --> \bibitem{Pernack} R. Pernack, PhD thesis, University of Rostock, Germany, (2004). \bibitem{Kupper} S. Kupper, PhD thesis, University of Ljubljana, Slovenia, (2007). 32q) probably remove ref. [30] E769, PRL77, (1996) 2392 (cf. comment (19) -- it seems that this reference is needed only for the 3rd paragraph of subsection 5.2 for which I propose a rephrasing.) With best regards, Dima.