How to Cite

Citing Journal Articles
Citations to journal articles should include elements that clearly identify the article. These identifying elements are used by citation matching services to make citations to the articles into live links and by citation indexes in determining which articles are being cited. The most useful of the references elements for identifying journal articles are:
source
For journal article citations, this is the title of the journal in which the cited article was published. (Publishers and archives typically establish authority lists of journal titles. For example, in PubMed Central processing, the journal title source is usually the NLM title abbreviation of the journal name: <source>Physiol Rev</source>. For book citations, the source is the title of the book: <source>Moby Dick</source>.)
article-title
Title of the journal article, typically in English. Usually this is the exact title as given in the print or display of the article: <article-title>The ethics of quackery and fraud in dentistry: a position paper</article-title>. Editorial added content, for example the word “[Retracted]”, should not be added to the title, but should follow the title as text or a <comment>.
volume
The volume number of the journal in which the article was published, if applicable.
issue
The issue number of the journal in which the article was published. The issue number element is typically just a simple counting number such as “4” or “35”, but some journals do simultaneous multiple issues, and in such cases both numbers should be placed inside the single <issue> element: <issue>4-5</issue>.
fpage
Page number on which the article starts. (Although many citations also list the last page on which the article can be found (<lpage>), current citation matchers place more emphasis on the first page.)
name
The name (typically the <surname>) of the first author or editor of the article.
year
The year of publication. Multiple publication years (“2009-2010”) can be recorded in two ways: as successive <year> elements:
...
<year iso-8601-date="2009">2009</year>&ndash;<year>2010</year>
...
or as a single combined year:
...
<year iso-8601-date="2009">2009&ndash;2010</year>
...
month
The month of publication (if present).
day
The day of publication if present. This is of lesser importance, but some citation matchers use it if it is available.
Citing Books
The majority of non-journal citations are for books, in whole or part. There are additional elements used in book citations that are rarely used for journals:
  • Publisher information (<publisher-name> and <publisher-loc>) is nearly always present for a cited book, and may be tagged to aid in identification.
  • Most modern books are assigned ISBN values (<isbn>). Occasionally a journal series will also have an ISBN.
  • Books series titles and other series information should be tagged in a <series> element.
  • The length or page count of books should be tagged as the <size> element (“250p.”, tagged in a mixed-citation as <size units="pages">250</size>p.). Citations to entire books should not use the elements <fpage>, <lpage>, or <page-range>.
  • Chapter titles (which may be called chapters, parts, modules, lessons, etc.) may be tagged with the <part-title> element.
Here is a typical book, tagged in both mixed- and element-citation styles:
<mixed-citation publication-type="book" publication-format="print">
 <collab-name>Joint Commission on Accreditation of Healthcare 
 Organizations</collab-name>. <source>Are you prepared? Hospital emergency 
 management checklist</source>. <publisher-loc>Oak Brook
 (IL)</publisher-loc>: <publisher-name>Joint Commission Resources</publisher-name>.
 Forthcoming 2006.</mixed-citation>

<element-citation publication-type="book" publication-format="print">
 <collab-name>Joint Commission on Accreditation of Healthcare Organizations</collab-name>
 <source>Are you prepared? Hospital emergency management checklist</source>
 <publisher-name>Joint Commission Resources</publisher-name>
 <publisher-loc>Oak Brook (IL)</publisher-loc>
 <comment>Forthcoming 2006</comment>
</element-citation>
Here is a book in a non-print format, tagged in both mixed- and element-citation styles:
<mixed-citation publication-type="book" publication-format="mpic">
 <source>Clinical tonometry</source> [motion picture]. <collab-name 
 collab-type="producer">Public Health Service Audiovisual 
 Facility</collab-name>, producer. <publisher-loc>[Washington]</publisher-loc>:
 <publisher-name>Department of Health, Education, and Welfare (US), 
 Public Health Service</publisher-name>; <year iso-8601-date="1965">1965</year>. 
 1 reel: silent, black &amp; white, 35mm.</mixed-citation>

<element-citation publication-type="book" publication-format="mpic">
 <source>Clinical tonometry</source>
 <comment>[motion picture]</comment>
 <collab-name collab-type="producer">Public Health Service Audiovisual Facility</collab-name>
 <publisher-loc>[Washington]</publisher-loc>
 <publisher-name>Department of Health, Education, and Welfare (US), 
  Public Health Service</publisher-name>
 <year iso-8601-date="1965">1965</year>
 <comment>1 reel: silent, black &amp; white, 35 mm</comment>
</element-citation>
Citing Data
Current publishing practice is to cite data sources in much the same manner that articles and books are cited. Such citations may be part of a regular Reference List or listed separately in their own list, either at the back of the article or in a Data Availability Statement. (See Data Availability Statement.)
Principles of Data Citation
The Force11 Joint Declaration of Data Citation Principles states (among other principles) that:
  • Data should be considered legitimate, citable products of research.
  • Data citations should be accorded the same importance in the scholarly record as citations of other research objects, such as publications.
  • In scholarly literature, whenever and wherever a claim relies upon data, the corresponding data should be cited.
  • A data citation should include a persistent method for identification that is machine actionable, globally unique, and widely used by a community.
  • Data citations should facilitate identification of, access to, and verification of the specific data that support a claim. Citations or citation metadata should include information about provenance and fixity sufficient to facilitate verifying that the specific timeslice, version, and/or granular portion of data retrieved subsequently is the same as was originally cited.
Data Citations in JATS
The JATS citation models are adequate to record most current practice in citing data even though data sets, protein sequences, and spreadsheets (to name a few data examples) are not tagged as uniformly by the industry as are cited journals and books.
Specific JATS structures that can assist in preserving data source information in a citation include:
  • <data-title> — The formal title or name of a cited data source (or a component of a cited data source) such as a dataset or protein structure.
    Since datasets can contain very complex relationships for citing data, both the <source> element and the <data-title> element may be needed within a single citation to describe different levels of the data source. The <data-title> is typically used as an equivalent of an article title (<article-title>). See samples below.
  • <version> — A full version statement, which may be only a number, for data or software that is cited or described.
    The content of this element may be a simple version number (such as “<version>16</version>” or “<version>XII</version>”). More complex version statements may contain a textual statement including dates that the dataset covers. Whether or not the content is more than a simple number, the @designator attribute of this element can be used to hold the simple numerical or alphabetic version number, if there is such a number: <version designator="16.2">16th version, second release</version>.
Describing how the Data Files were Used
For the purposes of citing data sources, three different uses of the data associated with an article can be recognized:
  • Generated Data: Included or referenced external data generated in the course of the study on which the article reports.
  • Analyzed Data: Referenced data analyzed in the course of the study on which the article reports, but that was not generated for the study. This may include publicly available datasets.
  • Non-analyzed Data: Referenced data neither generated nor analyzed during the study.
The @use-type attribute (again on either <mixed-citation> or <element-citation>) may be set to explain how the data has been used in the research that led to the article, for example, for distinguishing between: “generated-data”, “analyzed-data”, and “non-analyzed-data” (referenced data).
Note: In current practice, exactly how the data were used is probably material that only contributors can supply. Publishers and archives may have no reliable way to determine use, as there is typically nothing in the text that states usage.
Examples of Data Citations
We would like to thank the Force11 group for the data citation examples given below.
Protein Data Bank in Europe sample:
...
<ref>
 <mixed-citation publication-type="data"><person-group
 ><string-name>Kollman JM</string-name>, 
 <string-name>Charles EJ</string-name>, <string-name
 >Hansen JM</string-name></person-group>, 
  <year iso-8601-date="2014">2014</year>, <data-title>Cryo-EM structure of 
  the CTP synthetase filament</data-title>, <ext-link ext-link-type="uri" 
  xlink:href="http://www.ebi.ac.uk/pdbe/entry/EMD-2700">
  http://www.ebi.ac.uk/pdbe/entry/EMD-2700</ext-link>, Publicly available 
  from <source>The Electron Microscopy Data Bank (EMDB)</source>.</mixed-citation>
</ref>
...
GigaScience sample:
...
<ref>
 <mixed-citation publication-type="data">Zheng LY, 
  Guo XS, He B, Sun LJ, Pi CM, Jing H-C: Genome data from 
  [<ext-link ext-link-type="uri" xlink:href="http://dx.doi.org/10.5524/100012">
  http://dx.doi.org/10.5524/100012</ext-link>] <source>GigaScience</source> 
  <year iso-8601-date="2011">2011</year>.</mixed-citation>
</ref>
...
Data in figshare, referenced through a DOI:
...
<ref>
 <mixed-citation publication-type="data">Di Stefano B, Collombet S, 
  Graf T. <source>Figshare</source> <ext-link ext-link-type="doi" 
  assigning-authority="figshare" 
  xlink:href="http://dx.doi.org/10.6084/m9.figshare.939408">
  http://dx.doi.org/10.6084/m9.figshare.939408</ext-link> 
  (<year iso-8601-date="2014">2014</year>).</mixed-citation>
</ref>
...
Dryad Digital Repository, referenced through a DOI:
...
<ref>
 <mixed-citation publication-type="data"><person-group person-group-type="authors"
 ><string-name>Dubuis JO</string-name>, <string-name>Samanta R</string-name>, 
 <string-name>Gregor T</string-name></person-group> 
  (<year iso-8601-date="2013">2013</year>).  Data from: 
  <data-title>Accurate measurements of dynamics and reproducibility 
  in small genetic networks</data-title>. <source>Dryad Digital 
  Repository</source> doi:<pub-id pub-id-type="doi">10.5061/dryad.35h8v</pub-id>
 </mixed-citation>
</ref>
...
GenBank Protein sample:
...
<ref>
 <mixed-citation publication-type="data">
  <data-title>Homo sapiens cAMP responsive element binding protein 1 
  (CREB1), transcript variant A, mRNA</data-title>. <source>GenBank</source> 
  <ext-link ext-link-type="genbank" xlink:href="NM_004379.3">NM_004379.3</ext-link>.
 </mixed-citation>
</ref>
...
RNA Sequence sample:
...
<ref>
 <mixed-citation publication-type="data">Xu, J. <etal/> 
  <data-title>Cross-platform ultradeep transcriptomic profiling 
  of human reference RNA samples by RNA-Seq</data-title>. 
  <source>Sci. Data</source> <volume>1</volume>:<elocation-id>140020</elocation-id>.  
  doi: <pub-id pub-id-type="doi">10.1038/sdata.2014.20</pub-id> 
  (<year iso-8601-date="2014">2014</year>).</mixed-citation>
</ref>
...
Citing Standards
There is no unified best practice for citing standards documents, such as “ISO 9001”, in JATS citations, because there is some basic disagreement among JATS users on this topic.
Is a Standard a Book?
Recent analysis has shown that standards are cited in journal articles both as standards and as books.
  • As a standard: When standards are cited as standards, the publication type is @publication-type="standard". Such citations typically include the standard’s title and the standard designator (which is a simple string which holds the standards-body acronym, the standard number, and a year for dated standards, e.g., “ANSI/NISO Z39.96‐2015”). The standard designator is tagged as a <pub-id>, and the standard title is tagged as a <source>. These citations are typically minimal, and may contain nothing but the designator and the title.
    ANSI/NISO Z39.96‐2015. JATS: Journal Article Tag Suite.
  • As a book: When standards are cited as a book (currently more common in journal articles), the publication type may be either @publication-type="standard" or @publication-type="book". The most important difference is other included citation elements. These book citations typically include the standard designator (e.g., “ANSI/NISO Z39.96‐2015”), the standard title, a publisher name, a publisher location, and a publication year (which is in addition to the approval year that may be named in the standard’s designator). They may also tag other book features like ISBN and size.
    ANSI/NISO Z39.96‐2015. (2015). JATS: Journal Article Tag Suite. Baltimore, MD: National Information Standards Organization.
JATS allows both standard citations cited as standards and cited as books. How to tag a standard and how much standard metadata to tag is left to the JATS users.
Recommended practice, whether tagged as a book or a standard, if a publication is a standard, and can be recognized as such, the @publication-type value of the citation should be “standard”. It is also recommended practice to tag a standard designator (see next section) if possible, using <pub-id>. Whether a version number is part of a standard’s title or not is also a publisher decision.
The Standard Designator
A standard designator is like the nickname for a standard; it is the way standards are generally talked about and referenced. Lookup of standards in databases, including at Crossref, is typically accomplished by using the designator as the lookup key. A standard designator usually includes (just as text and not separately identified): the acronym of the standards publisher (ANSI/NISO, ASME, ASTM, DIN, IEEE, ISO, etc.), the standard identification number, and optionally a year.
As an example, here are three standard designators: “ANSI/NISO Z39.96-2019”, “ISO 12083”, and “Z39.96-2021”.
Standard Designators in JATS
  • In JATS citations (<mixed-citation> or <element-citation>), standard designators (if tagged at all) should be tagged using <pub-id> with a @pub-id-type of “std-designator”:
    <pub-id pub-id-type="std-designator" specific-use="dated"
     >ANSI/NISO Z39.96-2021</pub-id>
  • In JATS citations (<mixed-citation> or <element-citation>), some publishers view the standard designator as part of the standard title (<source>):
    <source>ANSI/NISO Z39.96-2021 JATS: Journal Article Tag
     Suite</source>
How to Tag a Standard as a Standard
When cited as a standard, the mixed citation or element citation should include:
  • The attribute @publication-type set to:
    <mixed-citation publication-type="standard"...>
  • When a standard is cited, the @publisher-type attribute should not be used.
  • A standard designator (such as “ANSI/NISO Z39.96-2021”, “ISO 12083”, or “Z39.96-2015”), tagged as <pub-id>.
    • The attribute @pub-id-type set to @pub-id-type="std-designator".
    • The attribute @specific-use can be given a value “dated” if the standard includes a year, and “undated” if not.
      <pub-id pub-id-type="std-designator" specific-use="dated"
       >ANSI/NISO Z39.96-2021</pub-id>
  • The title of the standard, tagged as <source>.
    <source>JATS: Journal Article Tag Suite</source>
  • Any other tagging is optional and typically omitted.
How to Tag a Standard as a Book
When cited as a book, the mixed citation or element citation may include any of the following:
  • A @publication-type attribute either set to @publication-type="standard" or @publication-type="book". Which value to use is a publisher decision, although it is considered best practice to tag a recognized standard as @publication-type="standard".
  • The title of the standard, tagged as <source>. For some publishers, this title will include the standard designator as well as the standard title.
    <source>JATS: Journal Article Tag Suite</source>
    
    <source>ANSI/NISO Z39.96-2021 JATS: Journal Article Tag
     Suite</source>
  • The standard designator (such as “ANSI/NISO Z39.96-2019”, “ISO 12083”, or “Z39.96-2019”), if it was not included as part of the source, although it may not be tagged at all. Recommended practice is to tag the designator separately using <pub-id>, so it can be used for online lookup.
    • The attribute @pub-id-type set to @pub-id-type="std-designator".
    • The attribute @specific-use can be given a value “dated” if the standard includes a year, and “undated” if not.
      <pub-id pub-id-type="std-designator" specific-use="dated"
       >ANSI/NISO Z39.96-2021</pub-id>
  • The publisher, tagged as <publisher-name>.
  • The publisher location, tagged as <publisher-loc>.
  • Date of the standard, as <year> if the date is displayed separately as well as part of the title or the designator.
  • Typical book tagging such as ISBN, contributor or collaboration, size, etc.
Note: When citing a standard, the @publisher-type attribute should not be used.
Standards-related deprecated JATS Elements/Attributes
  • In current JATS, the element <std> is deprecated and should not be used.
  • In current JATS, the element <std-organization> is deprecated and should not be used.
  • The value for @publisher-type of “standards-body” has been removed from the list of suggested values for the citation attribute @publisher-type. When a standard is cited, the @publisher-type attribute should not be used.
@pub-type for Conferences Materials
Cited conference papers and conference proceedings are not tagged as uniformly in the industry as are cited journals and books. At present, there is no industry-wide agreement on how to tag citations to papers presented at conferences, papers published in a conference proceedings, complete conference proceedings, or papers written for but not presented at a conference. Writers of citations and citation style guides, JATS users, publishers, archives, and vendors may disagree concerning:
  • What does @publication-type="conference" mean, and when can it be used? (For example, does a conference proceedings document use @publication-type="conference", @publication-type="book", @publication-type="conf-proc" or something else?)
  • Is the title of a paper in a conference proceedings an <article-title> or a <part-title>?
  • What is the content of <source> in a cited conference article?
  • How much of the information concerning the conference (name, dates, location) should one explicitly identify inside a citation?
Ultimately each organization needs to tag based on their business requirements for how they intend to use the XML, so this documentation has no best practice recommendations. Some of the more contentious issues are discussed below, with examples.
Type of Citations
A conference paper is an article-like document that may have been delivered at a conference, may have been published in a conference proceedings document, and/or may have been written to deliver at a conference but neither presented nor published in a proceedings.
Therefore citations to conference material may be references to:
  • Papers presented at a meeting
  • Papers intended for presentation at a meeting (but never given)
  • Papers published in a conference proceedings
  • Papers for which full information for the conference as well as the proceedings document is provided
  • Citation to a complete proceedings document
Some JATS users consider all these as @publication-type="conference". Other JATS users consider the first two to be @publication-type="conference" and the last three types to be @publication-type="book".
An Example of a Conference-related Citation
van Pelt, J, ..., editors. Development, dynamics, and pathology 
of neuronal networks: from molecules to functional circuits. Proceedings 
of the 23rd International Summer School of Brain Research; 2003 Aug 25-29; 
Royal Netherlands Academy of Arts and Sciences, 
Amsterdam, the Netherlands. Amsterdam: Elsevier; 2005. 385 p.
(Progress in brain research; vol. 147).
For the JATS user, the question is how to identify this material. Some JATS users would tag this as a @publication-type="conference", since it contains the word “Proceedings”, a conference date, and a conference location. Some JATS users would tag this as a @publication-type="book", since the item has a publisher, a publisher location, and the number of pages. Is this a reference to a conference proceedings (@publication-type="conf-proc")? Since “Progress in brain research” is a series and has an ISSN (research will tell us), is this a reference to a serial?
Papers Published in a Conference Proceedings Document
Type Conference — For some JATS users, @publication-type="conference" is used for both papers published in a proceedings and papers presented at meetings. Thus all conference-related material is cited as @publication-type="conference", and different components are tagged depending on which of the above types of citation the reference is considered to be.
Here is a citation to the above reference illustrating this style:
<mixed-citation publication-type="conference">
<person-group person-group-type="editor"><string-name><surname>van Pelt</surname>, 
<given-names>J</given-names></string-name>, <etal>...</etal>,
<role>editors</role></person-group>. <source>Development, dynamics, 
and pathology of neuronal networks: from molecules to functional circuits</source>. Proceedings of the <conf-name>23rd 
 International Summer School of Brain 
 Research</conf-name>; <conf-date>2003 Aug 25-29</conf-date>; 
<conf-sponsor>Royal Netherlands Academy of Arts and Sciences</conf-sponsor>, 
<conf-loc>Amsterdam, the Netherlands</conf-loc>. 
<publisher-loc>Amsterdam</publisher-loc>: 
<publisher-name>Elsevier</publisher-name>; 
<year>2005</year>. <size units="page">385</size> p. 
(<series>Progress in brain research</series>; <volume>vol. 147</volume>).
</mixed-citation>
with a possible variant of:
<mixed-citation publication-type="conference">
<person-group person-group-type="editor"><string-name><surname>van Pelt</surname>, 
<given-names>J</given-names></string-name>, <etal>...</etal>, 
<role>editors</role></person-group>. <source>Development, dynamics,
and pathology of neuronal networks: from molecules to functional circuits</source>. Proceedings of the <conf-name>23rd 
 International Summer School of Brain 
 Research</conf-name>; <conf-date>2003 Aug 25-29</conf-date>; <conf-loc>Royal 
Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands</conf-loc>. 
<publisher-loc>Amsterdam</publisher-loc>: 
<publisher-name>Elsevier</publisher-name>;
<year>2005</year>. <size units="page">385</size> p. 
(<series>Progress in brain research</series>; <volume>vol. 147</volume>).
</mixed-citation>
To these JATS users, the words “Development, dynamics, and pathology of neuronal networks: from molecules to functional circuits” are part of the proceedings title. If the individual paper were titled separately (which it is not in this citation), that would be tagged as an <article-title>.
Typed as a Book — Some JATS users consider a published conference proceedings to be a “book” in the broad sense of anything that looks or behaves like a book, may take an ISBN, and that provides publisher information.
Here is a citation to the same conference paper for the @publication-type="book":
<mixed-citation publication-type="book"><person-group person-group-type="editor">
<string-name><surname>van Pelt</surname>, 
<given-names> J.</given-names></string-name>,
<etal>et al.</etal></person-group> (<role>Eds.</role>). 
(<year>2005</year>). <source>Development, dynamics, and pathology of neuronal 
 networks: From molecules to functional circuits:  Proceedings of the 23rd International 
 Summer School of Brain Research, 2003 Aug 25-29, Royal Netherlands Academy of Arts and 
 Sciences, Amsterdam, the Netherlands</source>. 
 <publisher-loc>Amsterdam</publisher-loc>:  
 <publisher-name>Elsevier</publisher-name>. 
 <comment>385 p. </comment> 
 (<comment>Progress in brain science; vol. 147</comment>)</mixed-citation>
To these JATS users, a conference proceedings is not a document type:
“This is a book. Elsevier considers it a book (https://www.sciencedirect.com/science/journal/00796123/147/supp/C). It has an ISBN, editors, a preface, and lots of other book parts. It is sold on Amazon and textbook sites as a book. The metadata at Crossref has it typed as a book. This should be cited as a single volume in a book series.”
When tagged as a book, the title of the paper published in a proceedings becomes a <part-title>, treated as a chapter title.
Typed as Conference Proceedings — This same example could be tagged as a conference proceedings (with @publication-type="conf-proc") to distinguish between a paper presented at a conference or published in a proceedings and a full proceedings document. (See https://jats.nlm.nih.gov/publishing/tag-library/1.4d1/element/conf-sponsor.html)
<element-citation publication-type="conf-proc">
 <person-group person-group-type="editor">
  <name><surname>van Pelt</surname>
   <given-names>J</given-names></name>
 ...</person-group>
 <source>Development, dynamics, and pathology
  of neuronal networks: from molecules to functional circuits</source>
 <conf-name>Proceedings of the 23rd International Summer School of 
  Brain Research</conf-name>
 <conf-date iso-8601-date="2003-08-25">2003 Aug 25-29</conf-date>
 <conf-sponsor>Royal Netherlands Academy of Arts and Sciences, Amsterdam, 
  the Netherlands</conf-sponsor>
 <publisher-loc>Amsterdam</publisher-loc>
 <publisher-name>Elsevier</publisher-name>
 <year iso-8601-date="2005">2005</year><size units="pages">385 p</size>
 <comment>(Progress in brain research; vol. 147)</comment>
</element-citation>
Papers Presented at a Conference
JATS users also have different ways of treating a paper that was presented at a conference but not published in a proceedings document. As an example, consider this citation:
De, A., & Saha, A. (2015). A comparative study on different 
approaches of real time human emotion recognition based on facial expression 
detection. Paper presented at the 2015 International Conference on Advances 
in Computer Engineering and Applications (ICACEA), 19–20 March 2015.
Most JATS users consider any paper that was presented at a meeting to be typed @publication-type="conference". For some JATS users, a conference paper must be presented at the meeting to be typed @publication-type="conference", and a paper merely published in the proceedings would not be of type “conference”. In the following tagging, the citation is typed as a conference and the title of the paper that was presented is captured as an <article-title>:
<mixed-citation publication-type="conference">
<person-group person-group-type="author"><string-name><surname>De</surname>, 
 <given-names>A.</given-names></string-name>, &amp;  
 <string-name><surname>Saha</surname>, 
 <given-names>A.</given-names></string-name></person-group> 
 (<year>2015</year>). <article-title>A comparative study on different 
 approaches of real time human emotion recognition based on facial expression 
 detection</article-title>. Paper presented at the <conf-name>2015 
 International Conference on Advances in Computer Engineering and Applications 
 (ICACEA)</conf-name>, <conf-date>19-20 March 2015</conf-date>.
</mixed-citation>
However, some JATS users consider a paper presented at a conference but not published in a proceedings to be “unpublished”. Such unpublished conference papers (not part of a proceedings) are treated as standalone documents, and while tagged as @publication-type="conference", capture the title of the paper as a <source>.
<mixed-citation publication-type="conference">
<person-group person-group-type="author"><string-name><surname>De</surname>, 
 <given-names>A.</given-names></string-name>, &amp;  
 <string-name><surname>Saha</surname>, 
 <given-names>A.</given-names></string-name></person-group> 
 (<year>2015</year>). <source>A comparative study on different 
 approaches of real time human emotion recognition based on facial 
 expression detection</source>. <comment>Paper presented at the 
 2015 International Conference on Advances in Computer Engineering and 
 Applications (ICACEA), 19–20 March 2015</comment>.</mixed-citation>
How Much of the Conference Information Should Be Tagged
Should conference metadata within a citation be tagged at all? Should it be tagged as fully as possible? Somewhere in between? This is a business and processing as well as a technical decision.
Many citations are deposited with Crossref or other authority. The Crossref Conference Metadata Model is divided into two main elements:
  • event_metadata
  • proceedings_metadata
There are sufficient conference-related semantic elements in JATS citations to allow extraction of both kinds of conference metadata from a JATS citation, including:
Some JATS users choose to tag as much of this conference metadata as is practical, for Crossref deposit as well as their own metadata processing:
<mixed-citation publication-type="conference">
<person-group person-group-type="editor"><string-name><surname>van Pelt</surname>, 
 <given-names>J</given-names></string-name>, <etal>...</etal>, 
 <role>editors</role></person-group>. <source>Development, dynamics, 
 and pathology of neuronal networks: from molecules to functional circuits</source>. Proceedings of the <conf-name>23rd 
 International Summer School of Brain 
 Research</conf-name>;  <conf-date>2003 Aug 25-29</conf-date>; <conf-loc>Royal 
 Netherlands Academy of Arts and Sciences, Amsterdam, the Netherlands</conf-loc>. 
 <publisher-loc>Amsterdam</publisher-loc>: <publisher-name>Elsevier</publisher-name>; 
 <year>2005</year>. <size units="page">385</size> p. (<series>Progress in 
 brain research</series>; <volume>vol. 147</volume>).</mixed-citation>
On the other hand, at least one JATS user has expressed the opinion that:
“The reference in the JATS documentation is derived from a library catalog record. Catalog records historically were created as finding aids for people poking through card catalogs. Their goal was to point someone to a physical book sitting on a shelf, surrounded by books on the same or closely related topics. Catalogers usually didn’t make a clean or obvious distinction between core metadata and additional, descriptive metadata. In this case, the conference information is not part of the core metadata for the book; it was added by the cataloger.”
And they would prefer to tag that citation as:
<mixed-citation publication-type="book">
<person-group person-group-type="editor"><string-name><surname>van Pelt</surname>, 
 <given-names> J.</given-names></string-name>, <etal>et al.</etal></person-group> 
 (<role>Eds.</role>). (<year>2005</year>). <source>Development, dynamics, and 
 pathology of neuronal networks: From molecules to functional circuits:  Proceedings of the 
 23rd International Summer School of Brain Research, 2003 Aug 25-29, Royal Netherlands 
 Academy of Arts and Sciences, Amsterdam, the Netherlands</source>. 
 <publisher-loc>Amsterdam</publisher-loc>: 
 <publisher-name>Elsevier</publisher-name>. 
 <comment>385 p. </comment> (<comment>Progress in brain 
 science; vol. 147</comment>)</mixed-citation>
Conference Dates
Conference dates in citations (if they are tagged at all) are traditionally tagged in one of two forms:
  • as a single date (“May 2011”), or
  • as the first day and last day of the conference.
Either form could be stored in the <conf-date> element. For best practice, the dates that come initially from separate first and last elements should be combined; for example, the separate dates:
  <conf-start>August 4, 2010</conf-start>
  <conf-end>August 9, 2010</conf-end>
should be merged into a single conference date to become:
<conf-date iso-8601-date="2010-08-04">August 4, 2010 - August 9, 2010</conf-date>
Thus a tagged conference citation might look like this, tagged as an element citation:
<element-citation publication-type="paper">
 <name><surname>Thabet</surname><given-names>A</given-names></name>
 <article-title>Clinical value of two serial pulmonary embolism-protocol 
  CT studies performed within ten days</article-title>
 <conf-name>Annual Scientific Meeting and Postgraduate Course of 
  the American Society of Emergency Radiology</conf-name>
 <conf-date iso-8601-date="2006-09-27">2006 Sep 27&ndash;30</conf-date>
 <conf-loc>Washington, DC</conf-loc>
</element-citation>
And like this tagged as a mixed citation:
<mixed-citation publication-type="paper">
 <string-name><surname>Thabet</surname>, <given-names>A</given-names>
 </string-name>. <article-title>Clinical value of two serial pulmonary 
 embolism-protocol CT studies performed within ten days</article-title>. 
 <conf-name>Annual Scientific Meeting and Postgraduate Course of 
 the American Society of Emergency Radiology</conf-name>; 
 <conf-date iso-8601-date="2006-09-27">2006 Sep 27&ndash;30</conf-date>; 
 <conf-loc>Washington, DC</conf-loc>.</mixed-citation>
How much <source>: An Example of Our Differences
The JATS Standing Committee does not feel there is one correct way to understand, let alone tag, conference paper citations. To show the extent of the controversy, the following citation was presented to three JATS users:
Structural Carbohydrates in the Liver: Proceedings of the 
34th Falk Symposium, Held During Basel Liver Week, Basel, 
October 12-18, 1982 Cited from: https://books.google.com/books/about/Structural_Carbohydrates_in_the_Liver.html?id=87NqAAAAMAAJ.
So how to tag this? One JATS user suggested:
“It is common practice to include the entire conference name, date, and location in a proceedings title, so perhaps the location and date given in the example above are all part of the <source>.”
One user saw “Structural carbohydrates in the liver” as the article title and tagged the @publication-type as “conference”:
...<article-title>Structural carbohydrates in the liver</article-title>: 
 <source>proceedings of the 34th Falk Symposium</source>; 
 <conf-date>1982 Oct 12-18</conf-date>; <conf-loc>Basil, 
 Switzerland</conf-loc>. <publisher-loc>Boston</publisher-loc>: 
 <publisher-name>MTB Press</publisher-name>; <year>1983</year>. 
 <size units="page">701 p.</size>
Another user saw “Structural carbohydrates in the liver” as the first part of the book title rather than the title of an individual paper, so they would tag the citation as follows, with the @publication-type as “book”. (Note: This matches the record that comes up when you click on the WorldCat link from the Google Book page.)
...
<source>Structural Carbohydrates in the Liver: Proceedings of the
 34th Falk Symposium, Held During Basel Liver Week, Basel, 
 October 12-18, 1982</source>. <publisher-loc>Basel</publisher-loc>, 
 <year>1982</year>
And still another user agreed that initial phrase was part of the proceedings title, but tagged the <source> rather differently, with @publication-type tagged as “conf-proc”:
...
<source>Structural Carbohydrates in the Liver: Proceedings of the
 34th Falk Symposium</source>, Held During Basel Liver Week, 
 <publisher-loc>Basel</publisher-loc>, 
 <string-date iso-8601-date="10-12-1982"><month>October</month>, 
 <day>12</day>–<day>18</day>,  
 <year iso-8601-date="10-12-1982">1982</year></string-date>
Best Practice
JATS as a standard cannot recommend any best practices when the JATS users are so divided.