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FAQ: Article Versions and MEDLINE/PubMed Citations

This FAQ clarifies what is and is not a versioned citation from the National Library of Medicine point of view.

  1. What is a version?
    A version is a subsequent publication of a previously published article that incorporates new data or findings using a publishing practice designed specifically for rapidly communicating scientific results. Versioning distinguishes similar, related items that are published within days, weeks, or months of the original. Characteristics of subsequent versions include the retention of the publication date of the original article and the existence of a version date and version ID/number.
  2. What is not a version?
    The following are not included in the current NLM definition of a version:
    1. a re-publication of a previously published article that incorporates editorial changes to its content such as the correction of typographical errors in the text or author names. An erratum notice continues to be the appropriate mechanism in these cases to alert readers, and abstracting and indexing services.
    2. the various publication stages that a paper progresses through to the final publication itself (oftentimes known as the steps in a Content Management System); examples include manuscript version received, version accepted, version revised, version published ahead-of-print, and final version.
    3. an updated article that appears years after the original. NLM currently uses the Update of/Update in commentary links for this scenario.
    4. a "version of record" and other versioning terms as defined in this source: NISO RP-8-2008, Journal Article Versions (JAV): Recommendations of the NISO/ALPSP JAV Technical Working Group
      A Version of Record is: "A fixed version of a journal article that has been made available by any organization that acts as a publisher by formally and exclusively declaring the article "published"." This NISO definition applies to every published article.
  3. How does a versioned citation look in MEDLINE/PubMed?
    The PubMed display of versioned data follows guidance in the Bibliographic References standard (ANSI/NISO Z39.29: 2005 (R2010)).
    1. Summary Display
      Screen capture of PubMed Summary Display of a Versioned Citation.
      Figure 1: PubMed Summary Display of a Versioned Citation


    2. Abstract Display
      Screen capture of citationcontext menu.
      Figure 2: PubMed Abstract Display of a Versioned Citation


  4. What is the Publication Date vs. the Version Date?
    1. The Publication Date is the date the original publication was published. It will be retained in citations for subsequent versions. See 4a in Figure 1.
    2. The Version Date is the date the version was published; it is supplied to NLM by the publisher. For display purposes, the Version Date is appended in square brackets after the Publication Date in all PubMed formats except for the MEDLINE format. See 4b in Figure 1.
  5. What is a Version Number?
    1. NLM assigns its own unique Version Number. See 5a in see Figure 1.
      Behind the scenes in the XML data format, the Version Number created by NLM actually modifies the original PMID assigned to the citation for the first version, e.g.: 
      <PMID Version="2">20029611.2</PMID>
    2. Previous versions can be viewed by clicking on the "Other versions" link on the same line as the PMID in the Abstract display in PubMed. See 5b in Figure 2.
      NLM appends the Version Number to the base PMID to render a final, unique "decimal" PMID for subsequent versions, e.g.: 20029611.
  6. What is a VersionID?
    The publisher assigns its own version number and transmits it to NLM labeled VersionID as part of an XML data element. VersionID can be seen only in the PubMed XML display, e.g.:
    <MedlineCitation Owner="NLM" Status="In-Data-Review" VersionDate="2009/09/01" VersionID="2">
  7. How are other date fields for versioned citations handled?
    The DateCreated for the new version is the date that citation is added to PubMed. The EntrezDate is also new for the versioned citation so that the latest version displays at the top of the search results.
  8. How is a versioned citation retrieved in PubMed?
    1. Latest Version:
      Only the latest version is retrieved by all its citation access points. In other words, if the article title, abstract, or list of authors changes between versions, only the words or names present in the latest version are directly searchable in PubMed.
    2. Previous Version(s):
      A previous version can be retrieved only by a search on the combination of the PMID and Version Number, e.g.: 20029611.1
  9. Are versioned citations indexed with MeSH (Medical Subject Headings)?
    Yes, for MEDLINE journals each version will be indexed with MeSH and any appropriate links will be made (such as published errata links).
  10. As a publisher, is "versioning" a publishing model I want to use?
    It is up to the publisher to decide if the versioning publication model applies to some or all of the articles in a journal. Instructions for how to code a versioned citation in an XML citation submission to NLM are at: http://www.ncbi.nlm.nih.gov/books/NBK3828/#publisherhelp.How_should_I_submit_versio

    The NLM is implementing versioned citations only for journals whose citations are submitted electronically to NLM in XML format. Versioned citations will not be implemented for the journals that are still processed from receipt of the hard copy issue at NLM that is then scanned and undergoes OCR (Optical Character Recognition).

    An example of a journal using a versioning publishing model is PLoS Currents which participates in PMC (PubMed Central); PLoS Currents is cited in PubMed but is not a MEDLINE journal.

    To Discuss Versioning with NLM
    The NLM is interested in communicating with publishers before they decide to embark on a versioning publication model. Please contact NLM Customer Service.


    For More Information
    See Versioning in PubMed