- Online submission
- Submission policies
- General information for preparing manuscripts
- Cover letter
- Reporting summary and editorial policy checklist
- Format of manuscripts
- Author contributions
- Competing interests
- Data availability
- Computer code
- Supplementary information
- Related manuscripts
- General figure guidelines
- Figures for peer review
- Figures for publication
- Statistical guidelines
- Gene nomenclature
- Characterization of chemical and biomolecular materials
All submissions must be made via our online submission system. Using this system, authors can upload manuscript files (text, figures, videos) directly to our office and check on the status of their manuscripts during the review process. In addition, reviewers can access the manuscript online, which speeds up the review process. Revised manuscripts should be uploaded via the link provided in the editor's decision letter. Please do not submit revisions as new manuscripts.
Before a manuscript is submitted, please review our editorial policies, and ensure that the submission complies with our policy requirements.
We encourage all authors to register for an ORCID iD (ORCiD) and include their ORCiD in their author profile at or before manuscript submission. For more details on Springer Nature’s support of ORCiD, please follow this link.
Submission to Communications Medicine is taken to imply that there is no significant overlap between the submitted manuscript and any other papers from the same authors under consideration or in press elsewhere. (Abstracts or unrefereed web preprints do not compromise novelty). The authors must include copies of all related manuscripts with any overlap in authorship that are under consideration or in press elsewhere. If a related manuscript is submitted elsewhere while the manuscript is under consideration at Communications Medicine, a copy of the related manuscript must be sent to the editor.
The primary affiliation for each author should be the institution where the majority of their work was done. If an author has subsequently moved, the current address may also be stated.
If the manuscript includes personal communications, please provide a written statement of permission from any person who is quoted. E-mail permission messages are acceptable.
After acceptance, changes to the manuscript may be made so that papers conform to our style. The corresponding author is sent proofs and is welcome to discuss changes with the editors, but Communications Medicine reserves the right to make the final decision about matters of style and the size of figures.
The editors also reserve the right to reject a paper even after it has been accepted if it becomes apparent that there are serious problems with the scientific content or with violations of our publishing policies.
Communications Medicine does not charge submission fees or page charges. However, authors submitting to Communications Medicine are required to publish their work open access, through payment of an article processing charge (APC), in the case of eventual acceptance.
General information for preparing manuscripts
This guide outlines key points for preparing primary research manuscripts for submission to Communications Medicine.
The corresponding author should be familiar with the journal’s editorial policies and is solely responsible for communicating with the journal and managing communication between coauthors. Before submission, the corresponding author ensures that all authors are included in the author list and agree with its order, and that they are aware the manuscript is to be submitted.
If you wish to participate in double-blind peer review, please prepare your manuscript in a way that conceals the identities of all the authors and tick the appropriate box during online submission. We recommend that authors refer to our double-blind peer review guidelines when preparing a double-blind peer review manuscript. Please note that editors do not ensure that the paper is properly anonymised; that is the responsibility of the authors.
Reporting summary and editorial policy checklist
Life sciences research manuscripts sent for external review must include relevant details about several elements of experimental and analytical design. These requirements aim to improve the transparency of reporting and the reproducibility of published results. They focus on elements of methodological information that are frequently poorly reported (see more details on these elements here). If you are notified that your manuscript will be sent to review at Communications Medicine, you will be asked to complete the Nature Research Reporting Summary. The completed summary will be provided to the referees. Additional information about the reporting summary and the broader Nature Research initiative to support reproducible research is available here.
If your manuscript is sent for review, you will also be asked to complete the Nature Research Editorial Policy Checklist. This checklist is not sent to the reviewers but must be received by the editors before the paper can be sent for review.
Authors are encouraged to include both completed forms at the time of submission.
All primary research articles accepted will include the completed Nature Research Reporting summary as a supplementary file.
Authors should provide a cover letter that includes the affiliation and contact information for the corresponding author. The cover letter is an excellent opportunity to briefly discuss the context and importance of the submitted work and why it is appropriate for the journal. Please avoid repeating information that is already present in the abstract and introduction. The cover letter is not shared with the referees, and should be used to provide confidential information, such as conflicts of interest, and to declare any related work that is in press or submitted elsewhere. It is also appropriate to include suggested or excluded referees in the cover letter. We strive to ensure that the diversity of our reviewers reflects that of the broad scientific community, in terms of gender, ethnicity/race, geographic location and career stage. We ask that you keep this in mind when suggesting potential reviewers.
Due to our policy on Transparent Peer Review, you must clearly state in your cover letter whether you wish to OPT IN or OPT OUT of the publication of the reviewer reports when submitting the final version of your manuscript for publication.
Format of manuscripts
Manuscripts submitted to Communications Medicine do not need to adhere to our formatting requirements at the point of initial submission; formatting requirements only apply at the time of acceptance. For information on formatting non-primary research manuscripts, please consult the page on Communications Medicine content types.
We encourage authors to incorporate the manuscript text and figures into a single PDF or Microsoft Word file. Suitably high resolution figures may be inserted within the text at appropriate positions or grouped at the end. Each figure legend should be presented on the same page as its figure. We can accept LaTeX files at the acceptance stage, but before then please supply compiled PDFs.
Manuscripts published in Communications Medicine are not subject to in-depth copy editing as part of the production process. Authors are encouraged to seek copy editing or language editing services for their manuscripts, either before submission, or at the revision stage, should they feel it would benefit their manuscript. Such services include those provided by our affiliates Nature Research Editing Service and American Journal Experts. Please note that the use of Nature Research Editing Service is at the author's own expense and in no way implies that the article will be selected for peer review or accepted for publication.
Authors must ensure that their Methods section includes adequate experimental and characterization data necessary for others in the field to reproduce their work. Descriptions of standard protocols and experimental procedures should be given. Commercial suppliers of reagents or instrumentation should be identified. Sources for kits should be identified. Experimental protocols that describe the synthesis of compounds should be included. Authors should describe the experimental protocol in detail, referring to amounts of reagents in parentheses, when possible (e.g. 1.03 g, 0.100 mmol). Standard abbreviations for reagents and solvents are encouraged. Safety hazards posed by reagents or protocols should be identified clearly. Isolated mass and percent yields should be reported at the end of each protocol.
Communications Medicine uses standard Nature referencing style.
Schott, D. H., Collins, R. N. & Bretscher, A. Secretory vesicle transport velocity in living cells depends on the myosin V lever arm length. J. Cell Biol. 156, 35-39 (2002).
Bellin, D. L. et al. Electrochemical camera chip for simultaneous imaging of multiple metabolites in biofilms. Nat. Commun. 7, 10535; 10.1038/ncomms10535 (2016).
For papers with more than five authors include only the first author’s name followed by ‘et al.’.
Smith, J. Syntax of referencing in How to reference books (ed. Smith, S.) 180-181 (Macmillan, 2013).
Manaster, J. Sloth squeak. Scientific American Blog Network http://blogs.scientificamerican.com/psi-vid/2014/04/09/sloth-squeak (2014).
Hao, Z., AghaKouchak, A., Nakhjiri, N. & Farahmand, A. Global integrated drought monitoring and prediction system (GIDMaPS) data sets. figshare http://dx.doi.org/10.6084/m9.figshare.853801 (2014).
Communications Medicine requires an Author Contribution Statement that specifies the individual contributions of each co-author. For example: "A.P.M. 'contributed' Y and Z; B.T.R. 'contributed' Y," etc. Please see the Authorship section of our editorial policies for more details.
A competing interests statement is required for all accepted papers published in Communications Medicine. If there is no conflict of interest, a statement declaring this will still be included in the paper.
Communications Medicine requires a Data Availability Statement to be included in the submitted manuscript (see the section on Reporting standards and availability of data, materials, code and protocols in our editorial policies page for more information).
Any previously unreported custom computer code used to generate results reported in the manuscript that are central to the main claims must be made available to editors and referees upon request. Any practical issues preventing code sharing will be evaluated by the editors who reserve the right to decline the manuscript if important code is unavailable. At publication, Nature Research journals consider it best practice to release custom computer code in a way that allows readers to repeat the published results.
For all studies using custom code that is deemed central to the conclusions, a statement must be included in the Methods section, under the heading "Code availability", indicating whether and how the code can be accessed, including any restrictions.
Any Supplementary Information should be submitted with the manuscript and will be sent to referees during peer review. It is published online with accepted manuscripts. We request that authors avoid "data not shown" statements and instead make their data available via deposition in a public repository (see Availability of materials and data for more information). Any data necessary to evaluate the claims of the paper that are not available via a public depository should be provided as Supplementary Information.
Supplementary Information is not edited, typeset or proofed, so authors should ensure that it is clearly and succinctly presented at initial submission, and that the style and terminology conform to the rest of the paper. Please note that modification of Supplementary Information after the paper is published requires a formal correction, so authors are encouraged to check their Supplementary Information carefully before submitting the final version.
Further queries about submission and preparation of Supplementary Information should be directed to email: email@example.com.
It is a requirement of submission that you alert us to any related manuscripts with overlapping authorship that are under consideration (including under appeal) or in press at other journals (see our editorial policies on duplicate submissions for details). Copies of these manuscripts should be clearly marked and included as separate files with your submission. Abstracts or other unrefereed preprints do not compromise novelty.
General figure guidelines
Authors are responsible for obtaining permission to publish any figures or illustrations that are protected by copyright, including figures published elsewhere and pictures taken by professional photographers. The journal cannot publish images downloaded from the internet without appropriate permission.
Unnecessary figures should be avoided: data presented in small tables or histograms, for instance, can generally be stated briefly in the text instead. Figures should not contain more than one panel unless the parts are logically connected; each panel of a multipart figure should be sized so that the whole figure can be reduced by the same amount and reproduced at the smallest size at which essential details are visible.
Should your manuscript be accepted, you will receive more extensive instructions for final submission of display items. However, some guidelines for final figure preparation are included below if you wish to minimize later revisions and possible delays.
Figures should be numbered separately with Arabic numerals in the order of occurrence in the text of the manuscript. When appropriate, figures should include error bars. A description of the statistical treatment of error analysis should be included in the figure legend. Please note that schemes are not used; sequences of chemical reactions or experimental procedures should be submitted as figures, with appropriate captions. A limited number of uncaptioned graphics depicting chemical structures—each labelled with their name, by a defined abbreviation, or by the bold Arabic numeral—may be included in a manuscript.
Figure lettering should be in a clear, sans-serif typeface (for example, Helvetica); the same typeface in the same font size should be used for all figures in a paper. Use 'symbols' font for Greek letters. All display items should be on a white background, and should avoid excessive boxing, unnecessary colour, spurious decorative effects (such as three-dimensional 'skyscraper' histograms) and highly pixelated computer drawings. The vertical axis of histograms should not be truncated to exaggerate small differences. Labelling must be of sufficient size and contrast to be readable, even after appropriate reduction. The thinnest lines in the final figure should be no smaller than one point wide. Authors will see a proof that will include figures.
Figures divided into parts should be labelled with a lower-case bold a, b, and so on, in the same type size as used elsewhere in the figure. Lettering in figures should be in lower-case type, with only the first letter of each label capitalized. Units should have a single space between the number and the unit, and follow SI nomenclature (for example, ms rather than msec) or the nomenclature common to a particular field. Thousands should be separated by commas (1,000). Unusual units or abbreviations should be spelled out in full or defined in the legend. Scale bars should be used rather than magnification factors, with the length of the bar defined. In legends, please use verbal explanations such as "open red triangles" rather than visual queues.
Figures for peer review
At the initial submission stage authors should incorporate figures into the main article file, ensuring that any inserted figures are of sufficient quality to be clearly legible. If this is not possible in a combined manuscript file, authors should either submit separate high resolution figure files or deposit image data in a suitable repository (e.g. figshare) and use their option to provide a private sharing link for the referees to access it.
When submitting a final manuscript for publication, all figures must be uploaded as separate figure files ensuring that the image quality and formatting conforms to the specifications below.
Figures for publication
Each complete figure must be supplied as a separate file upload. Multi-part/panel figures must be prepared and arranged as a single image file (including all sub-parts; a, b, c, etc.). Please do not upload each panel individually.
Please read the digital images integrity and standards section of our editorial policies. When possible, we prefer to use original digital figures to ensure the highest-quality reproduction in the journal. For optimal results, prepare figures to fit A4 page-width. When creating and submitting digital files, please follow the guidelines below. Failure to do so, or to adhere to the following guidelines, can significantly delay publication of your work.
Authors are responsible for obtaining permission to publish any figures or illustrations that are protected by copyright, including figures published elsewhere and pictures taken by professional photographers. The journal cannot publish images downloaded from the internet without appropriate permission.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
- Provide images in RGB color and at 300 dpi or higher resolution.
- Use the same typeface (Arial or Helvetica) for all figures. Use symbol font for Greek letters.
- Use distinct colors with comparable visibility and avoid the use of red and green for contrast. Recoloring primary data, such as fluorescence images, to color-safe combinations such as green and magenta or other accessible color palettes is strongly encouraged. Use of the rainbow color scale should be avoided.
- Figures are best prepared at the size you would expect them to appear in print. At this size, the optimum font size is between 8pt.
- We prefer vector files with editable layers. Acceptable formats are:
.ai, .eps, .pdf, .ps and .svg for fully editable vector-based art; layered .psd and .tif for editable layered art; .psd, .tif, .png and .jpg for bitmap images; .ppt if fully editable and without styling effects; ChemDraw (.cdx) for chemical structures.
- Please refer to the Nature Research Style Guide for Chemical Structures for formatting of chemical structures.
If you would like to submit a suggestion for the featured image on our homepage with the final version of your manuscript, please also include the Image License to Publish form.
Comprehensive information on the statistical analyses used must be included in the paper. The Methods must include a statistics section with the following information.
Every article that contains statistical testing should state the name of the statistical test, the n value for each statistical analysis, the comparisons of interest, a justification for the use of that test (including, for example, a discussion of the normality of the data when the test is appropriate only for normal data), the alpha level for all tests, whether the tests were one-tailed or two-tailed, and the actual P value for each test (not merely "significant" or "P < 0.05"). It should be clear what statistical test was used to generate every P value. Use of the word "significant" should always be accompanied by a P value; otherwise, use "substantial," "considerable," etc.
Data sets should be summarized with descriptive statistics, which should include the n value for each data set, a clearly labelled measure of centre (such as the mean or the median), and a clearly labelled measure of variability (such as standard deviation or range). Ranges are more appropriate than standard deviations or standard errors for small data sets. Graphs should include clearly labelled error bars. Authors must state whether a number that follows the ± sign is a standard error (s.e.m.) or a standard deviation (s.d.).
When plotting data, we strongly encourage authors to use box-and-whisker plots or dot-plots in order to fully show data distribution. If using a bar chart, please note that individual data points must be overlaid on the bars. More about this policy can be found in this editorial from Communications Biology.
Authors must justify the use of a particular test and explain whether their data conform to the assumptions of the tests. Three errors are particularly common:
- Multiple comparisons: When making multiple statistical comparisons on a single data set, authors should explain how they adjusted the alpha level to avoid an inflated Type I error rate, or they should select statistical tests appropriate for multiple groups (such as ANOVA rather than a series of t-tests).
- Normal distribution: Many statistical tests require that the data be approximately normally distributed; when using these tests, authors should explain how they tested their data for normality. If the data do not meet the assumptions of the test, then a non-parametric alternative should be used instead.
- Small sample size: When the sample size is small (less than about 10), authors should use tests appropriate to small samples or justify their use of large-sample tests.
Authors should use approved nomenclature for gene symbols, and use symbols rather than italicized full names (for example Ttn, not titin). Please consult the appropriate nomenclature databases for correct gene names and symbols. A useful resource is Entrez Gene, available from NCBI.
Approved human gene symbols are provided by HUGO Gene Nomenclature Committee (HGNC), e-mail: firstname.lastname@example.org; see also www.genenames.org. Approved mouse symbols are provided by The Jackson Laboratory, e-mail: email@example.com; see also www.informatics.jax.org/mgihome/nomen.
For proposed gene names that are not already approved, please submit the gene symbols to the appropriate nomenclature committees as soon as possible, as these must be deposited and approved before publication of an article.
Avoid listing multiple names of genes (or proteins) separated by a slash, as in 'Oct4/Pou5f1', as this is ambiguous (it could mean a ratio, a complex, alternative names or different subunits). Use one name throughout and include any others at first mention: 'Oct4 (also known as Pou5f1)'.
For information about referencing human single-nucleotide variants, see this editorial from Nature Genetics.
Characterization of chemical and biomolecular materials
Communications Medicine is committed to publishing the highest-quality research. Manuscripts submitted to the journal will be held to rigorous standards with respect to experimental methods and characterization of compounds. Authors must provide adequate data to support their assignment of identity, purity and homogeneity for compounds and materials described in the manuscript. Editors and reviewers will be responsible for assessing the completeness of the characterization. Authors should provide a statement confirming the source, identity and purity of known compounds and biomolecules that are central to the scientific study, even if they are purchased or resynthesised using published methods.
Chemical nomenclature and abbreviations
Molecular structures are identified by bold, Arabic numerals assigned in order of presentation in the text. Once identified in the main text or a figure, compounds may be referred to by their name preferably using systematic IUPAC nomenclature, by a defined standard abbreviation, or by the bold Arabic numeral (as long as the compound is referred to consistently as one of these three). Unconventional or specialist abbreviations should be defined at their first occurrence in the text.
The Methods section should be written as concisely as possible but should contain all elements necessary to allow interpretation and replication of the results. We encourage the inclusion of specific sections for statistics, reagents and animal models. Experimental protocols that describe the synthesis of compounds must be included. Authors must describe the experimental protocol in detail, referring to amounts of each reagent in parentheses (e.g. 1.03 g, 0.100 mmol). The source for commercial compounds must be provided. Standard abbreviations for reagents and solvents are encouraged. Safety hazards posed by reagents or protocols must be identified clearly. Isolated mass and percent yields should be reported at the end of each protocol. Isomeric ratios of compounds obtained as an inseparable mixture must be quantified where possible. Authors are encouraged to share their step-by-step experimental protocols on a protocol sharing platform of their choice. Nature Research's Protocol Exchange is a free-to-use and open resource for protocols; protocols deposited in Protocol Exchange are citable and can be linked from the published article. More details can be found at www.nature.com/protocolexchange/about.
Chemical identity for organic and organometallic compounds should be established through spectroscopic analysis. Detailed spectral data for compounds should be provided in list form (see below). Figures containing spectra generally will not be published as a manuscript figure unless the data are directly relevant to the central conclusions of the paper. Example format for compound characterization data:
mp: 100–102 °C (lit.ref 99–101 °C); [α]D = -21.5 (0.1 M in n-hexane); 1H NMR (400 MHz, CDCl3): δ 9.30 (s, 1H), 7.55–7.41 (m, 6H), 5.61 (d, J = 5.5 Hz, 1H), 5.40 (d, J = 5.5 Hz, 1H), 4.93 (m, 1H), 4.20 (q, J = 8.5 Hz, 2H), 2.11 (s, 3H), 1.25 (t, J = 8.5 Hz, 3H); 13C NMR (125 MHz, CDCl3): δ 165.4, 165.0, 140.5, 138.7, 131.5, 129.2, 118.6, 84.2, 75.8, 66.7, 37.9, 20.1; IR (Nujol): 1765 cm-1; UV/Vis: λmax 267 nm; HRMS (m/z): [M]+ calcd. for C20H15Cl2NO5, 420.0406; found, 420.0412; analysis (calcd., found for C20H15Cl2NO5): C (57.16, 57.22), H (3.60, 3.61), Cl (16.87, 16.88), N (3.33, 3.33), O (19.04, 19.09).
Yield and sample purity
Yield and evidence of sample purity is required for each isolated compound. Methods for purity analysis depend on the compound class. For most organic and organometallic compounds, purity may be demonstrated by high-field 1H NMR and 13C NMR data, although elemental analysis (±0.4%) is encouraged. Quantitative analytical methods including chromatographic (GC, HPLC, etc.) or electrophoretic analyses may be used to demonstrate purity for small molecules and polymeric materials. Melting points for crystalline compounds should be reported. In cases where isolation of pure samples is not possible (intermediates, mixtures, unstable species) or where the obtained quantities are not sufficient to perform a full characterization, a statement must be given, indicating that the species were not isolated or fully characterized.
Standard peak listings (see formatting guidelines above) for 1H NMR and proton-decoupled 13C NMR should be provided for organic compounds. Other NMR data should be reported (31P NMR, 19F NMR, etc.) when appropriate. Authors are encouraged to include high-quality images of spectra that cover the full range of chemical shifts scanned. Specific NMR assignments should be listed after integration values. Multidimensional NMR or decoupling experiments are encouraged when possible. UV or IR spectral data may be reported for the identification of characteristic functional groups, when appropriate.
Characterization of chiral compounds
The enantiomeric composition of chiral compounds should be characterized using appropriate techniques, including polarimetry, NMR, single crystal XRD, or by correlation of HPLC or GC. The specific rotation should be reported. Composition may be reported as enantiomeric excess or ratio.
Authors should also provide mass spectral data to support molecular weight identity. High-resolution mass spectral (HRMS) data are preferred, and when m/z < 1,000, the calculated and found values should be within 0.003. When m/z > 1000, we expect an experimental value within 1 ppm of the calculated value.
Single-crystal X-ray diffraction
Crystalline solids may be characterized by single crystal XRD. Crystallography should be combined with other techniques as required to establish identity and purity. Manuscripts reporting new structures from crystallographic analysis should be accompanied by a standard crystallographic information file (.cif) and a structural figure with probability ellipsoids should be included in the main supplementary information file. The structure factors for each structure should also be submitted, preferably embedded in the main .cif file, although they may be provided as a separate .hkl and/or .fcf file. Use of the latest version of the program SHELXL, which embeds the structure factors information in the main .cif file, is encouraged. The structure factors and structural output must be checked using IUCr's CheckCIF routine and a PDF copy of the output included with the submission, explaining any A- or B-level alerts. Additionally, an explanation for all A- and B-level alerts must be given in the supplementary information. Crystallographic data for small molecules should be submitted to the Cambridge Structural Database and the deposition number referenced in the manuscript. Full access must be provided on publication.
Solid state compounds
The homogeneity and purity of solid state compounds may be characterized by solid state NMR, powder X-ray diffraction data and where possible compared to calculated diffraction patterns.
Combinatorial compound libraries
Authors describing the preparation of combinatorial libraries should include standard characterization data for a diverse panel of library components.
For new biopolymeric materials (oligosaccharides, peptides, nucleic acids, etc.), direct structural analysis by NMR spectroscopic methods may not be possible. In these cases, authors must provide evidence of identity based on sequence (when appropriate) and mass spectral characterization.
Authors should provide sequencing or functional data that validates the identity of their biological constructs (plasmids, fusion proteins, site-directed mutants, etc.) either in the manuscript text, supplementary information, or the Methods section, as appropriate.
Chemical probe data
Manuscripts that report the identification and validation of new chemical probes are encouraged to submit their probes to the Chemical Probe Portal.
Small-molecule high-throughput screening data
Manuscripts reporting high-throughput screens of small-molecule libraries should include a supplementary table summarising the assay, library, screen and post-screen analysis. A template and instructions for preparing the high-throughput screening table are available.
Macromolecular structural data
Manuscripts reporting macromolecular structures should contain a table summarising structural and refinement statistics. Templates for such tables describing cryo-EM, NMR and X-ray crystallography data are available. To facilitate assessment of the quality of the structural data, a stereo image of a portion of the electron density map (for crystallography papers) or of the superimposed lowest energy structures (>10; for NMR papers) should be provided with the submitted manuscript. If the reported structure represents a novel overall fold, a stereo image of the entire structure (as a backbone trace) should also be provided. For cryo-EM structures, a representative micrograph showing individual particles should be provided in the submission. Crystallographic data for macromolecules must be submitted to the Worldwide Protein Data Bank (wwPDB), NMR data must be submitted to the Biological Magnetic Resonance Data Bank (BMRB) and cryo-EM data must be submitted to the Electron Microscopy Data Bank (EMDB). Deposition numbers must be referenced in the data availability statement in the manuscript. Full access must be provided on publication.
Microscopy images should be representative of the wider sample and labelled with scale bars. Full details for the reporting of microscopy experiments can be found on our policy page.
When electronic structure calculations are reported in the manuscript, the atomic coordinates of the optimised computational models should be provided. Codes and software should be available and properly referenced in the article and/or supplementary information. Input parameters, basis sets and coordinates of the input and output structures must be reported. If relative energies are reported, absolute energies should be provided in the supplementary information. For molecular dynamics trajectories, at least the initial and final configurations should be supplied. We encourage you to make them available by uploading the structures in any of the existing data repositories (see e.g. https://www.nature.com/sdata/policies/repositories). Alternatively, they can be supplied as a separate supplementary data file (ideally as a plain, unformatted text file).