1. This is a nice paper on the construction of the LAGOS database, written to provide detailed guidance for similar and related efforts. It comes at an appropriate time, given the need for such integrative open-data products and tools in multiple disciplines. The main text is written at a level that should make it extremely accessible for nontechnical readers, e.g., academic and agency scientists without database or informatics experience, or policymakers and representatives of funding agencies - and this is highly valuable, because it presents the intellectual, logistic, and financial challenges of such an effort, including the importance of citation of original data, documentation of transformations, and the hard decisions like leaving out parts of datasets (e.g., acid-base chemistry data). The Additional Files provide information that will be of interest and use at a technical level. I anticipate using this publication as an example and an educational tool for discussion with colleagues and students in my own domain, geoscience.

2. Minor essential revisions are given in the attached pdf. Really not much but a couple typos and queries. Level of interest An article of importance in its field Quality of written English Acceptable Statistical review No, the manuscript does not need to be seen by a statistician. Declaration of competing interests I have no competing interests.

Attachment: http://www.gigasciencejournal.com/manuscript/review/attachment/2054267101625732.pdf

Authors' response to reviewers: (http://www.gigasciencejournal.com/imedia/1248946842171461_comment.pdf)