Dear Peter and Bernhard, Your paper is well written and presents a well-done analysis. Please find below my comments and questions. Sorry for delay in answering. Best regards, Sasha. _______________________________________________________________________ Comments page 1, para 2: one can add another paper for charmonium: "charmonium [14,15]" adding the paper on psi' sect.2, para 2, line 5: "their position were" --> "their positions were" page 3, para 2: Strictly speaking, OTR pitches are 8.7 and 17.4 mm due to hexagonal geometry. I would propose to write "5 mm and 10 mm cell diameters". sect.3, end of para 1: "Therefore only about 10% of the events contain more than one interaction". Assuming Poisson distribution with mean 0.17, one can get 1.3% of the events contain more than one interaction (1-exp(-0.17)*(1+0.17)). Why there is such a large discrepancy? Table 2: Cut on zeta(D0) for D*+ is not explained. Why there are no cuts on d(D) for the cases of D+ and D*+ ? sect.3.2, para 1: figure 2, figure 3, figure 4 --> figures 2-4 page 8, para 2: Why background for D*+ was taken as a(q1/2+bq3/2)? Were other functions tried? Is it known that background should go to zero at q=0? (this is probably not very supported by the data, and besides the background on the right of the peak seems to be smaller than the average of the data points) page 8, para 3: PDG gives m = 1968.2 +- 1.4 MeV for D+s. Can you calculate the deviation from our value more exactly? Probably it will be less than two standard deviations. Figs.2-4: it would be good to put labels D0, D+, D+s, D*+ on the right of plots. Otherwise it is hard to remember the channel. It would be also good to give definition of q in the axis caption in Fig.4. Fig.2a: Except not very good description of the background from partially reconstructed charm decays, there is also a small bump in the background at m=1.55 GeV. Is it physical one or some artifact of drawing? sect.4, last para: Reference [25] is not ordered. page 11, last para: table 6, table 7, table 8 --> tables 6-8 Table 5: systematic uncertainty due to "event counting" can sound a bit mysterious Table 8: Ds --> D+s "first column" should be "first row"? It is not clear why there are D*+ which are not present in D0 sample. Fig.5: In the label for D+s put superscript "+" directly to the right of "D". In the same plot put a data point for E769 result. You give points for NA27 and NA16 results, but in the list of references the publication of these experiments have no name of these collaborations. Therefore I would propose to put NA16 and NA27 instead of LEBC-EHS which tells nothing to the reader. page 13, last para: Where PDG has the value (89.1+-4.1)% ? The last sentence about correlations seems to describe the value 87.4+-8.2+-12.6 mub, then it would be natural to put it after the first sentence of the paragraph. page 14, last para: If you fit and beta, you get chi2/ndf=0.82 but if you fix beta to 6, you get chi2/ndf=0.81. But then the first result is not a global minimum of chi2/ndf! Should and beta be the same for all species of D mesons including also the resonances? What data and MC say? page 15, end of first para: The part beginning with ", an extension of (11)" is difficult to read after the previous part in brackets. Since actually Eq.(2) was already discussed, I would propose to remove this part. sect.5.3: You cite several times PDG [24], but I wasn't able to find these numbers in PDG. Could you please tell where to look? You refer to results of E769 and NA27 - can references and values of the ratios be given to justify that the agreement is good? Can definition of P(V) be given? Fig.7: What does the solid line correspond to? If the world average is P(V) = 0.59, why do you draw the dotted line for P(V) = 0.6 ? Sect.5.4: You compare your results for the asymmetries with E769 but don't give their value. It would be good to give it. Why the systematic uncertainty of the weighted average is 0.01 - so small? Which version of Pythia do you use? There are papers cited in [1] that tuning Pythia allows to achieve a good description of asymmetries. page 17, last para: "ratio in two ways" - can you be more specific? page 18, para 1: "are in good agreement with the predictions derived from Pythia" - do you consider 1.5 standard deviations in sect.5.4 as good agreement? As it was already commented, the key is what version of Pythia is used and how it is tuned, but you mention only results 0.22-0.24 from Pythia. Possibly we can write in Summary about good agreement with other measurements. And possible add discussion of Pythia results. Put Acknowledgment section so that Collaboration could comment. References: You wrote that the paper is intended for EJP, and conforms in style to the requirements of the journal. Could you please check whether it is really so? I saw other style of References in the paper in this journal. Also ways of writing references to figures "Fig." should be in the same style. [1] Lourenco has a special accept under "c", Woehri is written with umlaut. [4,5] Specify NA16 and NA27 collaborations. [23] Refer to the public version of the luminosity paper. HERA-B has published some preliminary results on open charm production e.g. in EPJ C43 (2005) 179 and also some data given in Note added in proof in [1]. Publishing of this paper should supersede all these preliminary results and discussions. Therefore it seems to me that we should give the final version of all the values mentioned in these publications. Could you please check that this is done? For example, Note added in proof in [1] mentions: "According to Pythia, version 6.326, the HERA-B xF window covers slightly different fractions of full phase space for the leading and non-leading D mesons, because they have different rapidity distributions: 49% for the D+ and D0; 58% for the D- and D0bar". If this is HERA-B result, then it would be nice to include it in the final publication. If not, do we agree with these values? ________________________________________________________________________ TeXnical Comments Title: move "in" to the beginning of the second line page 1, last line: "present work presents" --> "present work provides" sect.2, para 1: "e-p" --> "$e-p$" sect.2, para 2: 50x70 --> $50\times70$ sect.2, para 2: write mm, MeV, GeV, etc. in upright font, e.g. 10--15~mm (the same in pages 6,7 and others) put a space before unit, e.g. 500~$\mu$m page 3, end of para 1: put long dashes "-" --> "--" or "---" paramatrized --> parametrized sect.4, eq.(1) put large square brackets \left[.....\right] eq.(2) write e^-... as exponent: exp(-....) Table 7: labels D0, D+, D+s, D*+ would look better if centered in the corresponding column page 13, last para: D-meson --> $D$-meson (by the way, is dash necessary here?) page 14: write ndf in upright font. Sect 5.3: write Br (for Branching) in upright font. Sect.5.4, line 2: put a wide bar in $\widebar{D}^0$. PDG does it this way. Sect.5.4, line 2 from end: "i.e. " --> "i.e.\ "