TITLE & ABSTRACT: You use the word spectral diagnostics several times with the implication that the readers should know exactly what you are going to do with them, or what they are for -- instead I would suggest being specific about the science that is being done with the diagnostics. So for example -- an alternate title could be "Distinguishing AGN, starbursts, HII nuclei using MIR Spectral Diagnostics from SINGS" -- I think SINGS should be included in the title. --I will query the team about the title Similarly I recommend removing (or at least condensing) the three sentences starting with "Here we present... Various combination.. Our main result.. " into one sentence that is the main point of this paper and is stated in the next line where you say "We find that both starbursting nuclei.." --I've condensed things (removed one preliminary sentence), rearranged some others. ABSTRACT: I don't understand the sentence that starts with "In fact, a set of regions..." -- which set? what regions? and what three diagrams? -- none of these have been defined yet -- can you make it specific and state exactly the results here. --Don't you think it will get quite ugly to say three times things like Line1/Line2 vs Line3/Line4, etc? In the next line -- "We also find that, compared to..." - this is another confusing line because earlier you have said they separate well - now with the clause "especially for low-metallicity region.." implies that you have found something specific that distinguishes AGN, starburst and extranucs and that thing is metallicity... but this is not really what you are intending to say right? You are just trying to emphasize that low metallicity regions in general separate out in the MIR diagnostics -- may be I am mistaken? --Thanks. I have clarified this by adding "extranuclear" before "environments". Last line.. "we show that strong low-ionization..." -- in the abstract I think you should say what these lines are.. --Done INTRODUCTION: The second half of the first paragraph in the introduction is a little confusing. You imply that Genzel's group did something with IR and PAH features and they found a different result than the optical studies which found more AGN domination -- but then you give Taniguchi's result saying that the resolution lies in LINER nuclei dominated by shock -- can you elaborate on this -- this part is confusing. I don't see how the shocks and SNe winds can resolve this controversy. Similarly add the main finding from the last line of studies -- you say they have used ISO to observe Galactic HII and starbursting nuclei -- and so what did they find? --Added I think that your last line of the intro is perfect and should be moved to the beginning of the introduction as well as in the abstract -- it captures the main point of this paper as well as all of the other discussions. --Done (claus suggested I include a line like this - thanks for letting me know where I could more optimally place it!) I ended up putting it at the beginning of the intro like you said, but I only rearranged the abstract a bit (plus condensed as you suggested above). SECTION 3.1, page 4: Are the optical and IR regions always centered -- these two sentences starting with "Furthermore the extraction apertures.. and the next one" seem to imply that the optical and IR are always centered.. but I recall that not being the case when we did the ex-nuc selections. --Yes, they are always centered on the optical centers. I have indicated in the table that this centering is off for the IR emission in NGC 5408. SECTION 4.1 Line 2-4: Recommend putting in the ionization potentials next to these lines along with their wavelengths. Sentence starting with "All these lines except Si II come.." -- needs a reference. Same with the next line regarding the Si II coming from different parts of the ISM. --Done SECTION 4.2: Line beginning with "The 6.2 micron feature is perhaps the one strong..." -- replace one with only, and perhaps say "The 6.2 micron feature is the only strong IR PAH signature.." --Done SECTION 5.1: I am so confused by the back and forth between Seyferts and LINERS. Are they the same - are they different. Is Figure 2 supposed to be showing how to distinguish them. And then the sentence "As for Seyferts, the optical properties of LINERS are consistent.." - that totally confused me. Perhaps this is obvious to AGN types...? --This is one of those instances that I have to try and balance multiple comments that go in different directions. I was asked to further explain LINERs. I did this almost straight out of what is said in Kauffmann et al, which I reference. Readers can go to this paper if they want more information. Last paragraph, page 7: The extinctions of A_v = 1 - 4.1 -- are these consistent with Ho et al. 400 nuclei survey? --Yes, and I reference Ho et al. in the Summary. page 8 - top line - Did Smith et al. 2004 show that OIV comes from accretion powered disks than star formation or should this be a different reference? Line 3, page 8 - "Furthermore studies show.." - change "save" -> "except", and add the words "those that" in between `such as` and `arise in AGN`. --Done Second para, page 8 - I realize you are trying to show that the inverse of 2.55 ~ 1/2.65 but that is strange notation -- I think if you put the correct decimal number and put 1/2.65 in parenthesis or leave it in words - that would be better. --I have removed this part of the discussion - as Lee correctly points out, I was explaining too much of my preliminary thinking rather than just describing the data. Top line, page 9: SiII(XDR) and SiII(PDR) -- are these different lines or the same line -- I think the same but the way it is written may be confusing to the non-expert in the field. SUMMARY: Para 2, line 1: note that the line ratio runs over .. this also happened earlier somewhere -- just FYI. --Thanks - the editor fixes that (I don't know how). FIGURE 2: Can you shade in the Seyferts area to distinguish it from LINERS? if they are supposed to be differentiated by this diagram? --The main goal is to differentiate Seyferts from star-forming.