NLM Citation Model


Structured citation model to assist users creating “new” content; the model loosely reflects the NLM’s style in that it allows the tagging of all “legal” NLM citations and enforces the sequence in which content must appear if it is present.


Note: This model does not provide guidance on what information is required for each type of cited content. Moreover, the model assumes that punctuation between the parts of a citation will be generated on display or on export from the XML tagged according to this Tag Set to XML for another use. For extensive examples of formatted <nlm-citation>s see: Sample PubMed Central Citations. To see tagged versions of these examples, see: Sample PubMed Central Citations - XML Tagged.


citation-type Type of Citation
id Identifier
xlink:actuate Actuating the Link
xlink:href Href (Linking Mechanism)
xlink:role Role of the Link
xlink:show Showing the Link
xlink:title Title of the Link
xlink:type Type of Link
xmlns:xlink XLink Namespace Declaration

Related Elements

There are two kinds of citations in this tag set; the <citation> element is free form to accommodate many styles of references, while the other element (<nlm-citation>) has a rigid structure of elements within it.

Model Information

Content Model

<!ELEMENT  nlm-citation
                        ((person-group | collab)*,
                         (article-title | trans-title)*,
                         source?, patent?, trans-source?, year?,
                         ((month?, day?, time-stamp?) | season?),
                         access-date?, volume?, edition?,
                         conf-name?, conf-date?, conf-loc?,
                         (issue | supplement)*, publisher-loc?,
                         publisher-name?, (fpage?, lpage?)*,
                         page-count?, series?, comment*, pub-id*,
                         annotation?)                                >


The following, in order:

This element may be contained in:

<p> Paragraph; <ref> Reference Item; <td> Table Data Cell (XHTML table model); <th> Table Header Cell (XHTML table model)

Tagged Example

<nlm-citation citation-type="journal">
<article-title>Electrogastrographic study of patients with 
unexplained nausea, bloating and vomiting</article-title>