<supplementary-material> Supplementary Material Metadata

Container element for a description of, and possibly a pointer to, external resources that support the article, but which are not part of the content of the article.


Supplemental material is used to add detail, background, or context to an article by providing, for example, multimedia objects such as audio clips and applets; additional XML-tagged sections, tables, or figures; raw data in a spreadsheet; or a software application in a repository. Supplementary material includes resources such as the following:
  • Voluminous material (such as a genomic database or the multiple data sets behind a work that abstracts the highlights of those datasets) that supports the conclusions of the narrative but can never accompany an article based on sheer mass;
  • “Extra” tables that do not display with the work, but that record the measurements on which the article is based (for example, tables that need to be available so the peer reviewers can check the article content);
  • Material added to the work for enhancement purposes, such as a quiz, an instructional video, the 3-minute version of the reaction that was described in the work with narrative and a few still images, a form that can be filled out or copied, or similar material;
  • A movie, MP3 file, or other binary material that is not directly part of the content of the article; and
  • The last several figures of the work that could not be included as part of the base work for stylistic considerations or space limitations.
An object that cannot be fully represented in print (such as a movie, sound file, or animation) should not automatically be considered supplemental. If the object is necessary for understanding the article (in other words, the object is “integral” as defined by NISO RP-15-2013, discussed below), it should be tagged at the appropriate location in the text using the <media> element.
The element is used in two contexts:
  • Inside the article metadata (<article-meta>) as an alert to the existence of supplementary material so that such material can be accessed from the article; and
  • As part of the textual narrative flow, where it is similar to a <fig>, in that it may take a caption and can be positioned as a floating or anchored object.
    For this usage, the @position attribute may be used to indicate whether the element must be anchored at its exact location within the text or whether it may float (for example, to the top of the next page, into the next column, to the end of a logical file, or within a separate window).
Contents of the Supplementary Material Element
The <supplementary-material> element does not contain the supplementary object(s), even if the objects are expressed in XML; supplementary objects are external to the XML article rather than part of the XML article. The <supplementary-material> element contains descriptions of the object(s), and it may also, but is not required to, contain a pointer to the objects(s). For example, if the supplementary object is an additional graphic, that graphic is described in the supplementary material but not held there. The <graphic> element that is permissible inside <supplementary-material> is intended for a description of an object, not to hold the object. For example, a <supplementary-material> element could contain a description of an animation, including the first frame of the animation (tagged as a <graphic> element), a caption describing the animation, and a cross-reference made to the external file that holds the full animation.
Associating Supplementary Data with a Figure or Table
When the data (such as a spreadsheet or dataset) associated with a document has been described using a <supplementary-material> element, then a figure, table, or similar display object can use an <xref> to point to that <supplementary-material>. This provides a mechanism to expose the data behind the figure or table. For example, assume that a figure (<fig>) is associated with three pieces of supplementary material (each described in a <supplementary-material> element). Three cross references (<xref>) can be embedded in the figure tagging to associate the figure with all three supplementary items, which may be datasets, additional figures, spreadsheets, etc. Note that a figure and its three supporting data objects are described in one figure and three supplementary material objects, which are connected by internal cross-references (<xref> elements), rather than as a figure group (<fig-group>) even if the 3 associated objects are figures.
Each figure within a <fig-group> and table within a <table-wrap-group> may contain its own <xref> elements to make this internal connection. External connections can also be made using one or more <ext-link> elements within a figure or table tagging.
The @mimetype attribute may be used to identify a file type for a <supplementary-material> element.

Relationship to NISO Supplemental Material Best Practices

NISO RP-15-2013 Recommended Practices for Online Supplemental Journal Article Materials (https://groups.niso.org/higherlogic/ws/public/download/10055) and NISO JATS have identical concepts for “additional” and “integral” material that comprises an article, but slightly different practice concerning whether supplementary material is integral or additional.
Both NISO JATS and NISO RP-15-2013 define:
  • integral content as “material that is essential for the full understanding of the work by the general scientist or reader in the journal’s discipline”, and
  • additional content as “supplemental material that provides additional, relevant, and useful expansion of the article in the form of text, tables, figures, multimedia, or data, and that may aid any reader to achieve deeper understanding of the current work through added detail and context. Additional Content … is not essential to the understanding of the article.”
The two differ in that, for NISO RP-15-2013, “integral content” may be part of an article or it may be part of the supplementary material for the article, that is, NISO RP-15-2013 allows supplementary material to be “integral”. For NISO JATS, which predates NISO RP-15-2013, all integral material is part of the base article (inside the <article> element), and all supplementary material is external to the article.
Relation to Other Journal Tag Sets
The <supplementary-material> element has a similar function to the <audiovisual> element in some XML tag sets and the <unprinted-item> element (used only for electronic files) in other tag sets.
Related Elements
This Suite contains several elements that can describe and point to graphical material: <graphic>, <inline-graphic>, <media>, <inline-media>, <supplementary-material>, and <inline-supplementary-material>. The elements <graphic> and <inline-graphic> contain a pointer to a still image (such as a photograph, diagram, line drawing, etc.) that is part of the document. The elements <media> and <inline-media> contain a pointer to a non-textual object (typically a binary such as an audio clip, dataset, or animation that cannot be displayed in print) that is integral to the document’s content, where  “integral” means that the media object is discussed within (and possibly displayed within) the document; the media object is part of the document.
In contrast, the elements <supplementary-material> and <inline-supplementary-material> are used to describe both XML material (textual material such as figures, tables, and sections) and non-textual material (such as graphics, films, audio clips, datasets, or other material) that are considered to be “additional material” (non-integral) accompanying a document. Like <graphic>, <inline-graphic>, <inline-media>, and <media>, the supplementary material elements never contain the object they describe, even if it is an XML object such as a figure, although they may point to it.
The element <inline-supplementary-material> is used to mark up references to additional material, where the reference appears within the regular flow of the text and does not have a preview image or separate caption. The <supplementary-material> element is used to describe a more complicated reference, where the description of the supplementary object resembles a figure in that it can be positioned as a floating or anchored object, may take a caption, and may use graphics or tables in the description of the object.

Base Attributes


Models and Context
May be contained in
Content Model
<!ELEMENT  supplementary-material
                        %supplementary-material-model;               >
Expanded Content Model

((object-id)*, (label)*, (caption)*, (abstract)*, (kwd-group)*, (subj-group)*, (alt-text | long-desc | email | ext-link | uri)*, (disp-formula | disp-formula-group | chem-struct-wrap | disp-quote | speech | statement | verse-group | table-wrap | p | def-list | list | alternatives | array | code | graphic | media | preformat | xref)*, (attrib | permissions)*)

Tagged Samples
Empty link to supplementary resource
  <contrib contrib-type="author">
   <collab collab-type="committee">Accredited Standards Committee S3, 
 <fpage seq="1">1</fpage>
 <supplementary-material mime-subtype="zip" mimetype="application"
<supplementary-material> structure describing a supplementary resource
<article dtd-version="1.3">
  <supplementary-material id="S1" xmlns:xlink="http://www.w3.org/1999/xlink"
    xlink:title="local_file" xlink:href="1471-2105-1-1-s1.pdf"
    <p>Supplementary PDF file supplied by authors.</p>
  <p>RNAPs seem to have arisen twice in evolution
   (see the <inline-supplementary-material
   xlink:title="local_file" xlink:href="timeline">
   Timeline</inline-supplementary-material>). A large
   family of multisubunit RNAPs includes bacterial
   enzymes, archeal enzymes, eukaryotic nuclear RNAPs,
   plastid-encoded chloroplast RNAPs, and RNAPs from
   some eukaryotic viruses. ...</p>
Supplementary material section
Supplementary material descriptions gathered into a section with links from figures, tables, etc. in the text
<fig id="fig1">
 <label>Figure 1</label>
 <caption id="fig1-caption">
  <title>Orthogroup clustering analysis</title>
  <p id="fig1-caption-p1">Lorem ipsum dolor sit amet</p>
 <graphic id="fig1-graphic" mime-subtype="jpeg" 
   mimetype="image" xlink:href="fig1.jpg" />
 <xref ref-type="supplementary-material" rid="source-data-1" />
<sec sec-type="supplementary-files">
 <title>Supplementary Files</title>
 <supplementary-material id="source-data-1" content-type="sdata" 
   mimetype="text" mime-subtype="csv" xlink:href="source-data-1.csv">
  <label>Supplementary File 1</label>
   <title>Orthogroup clustering analysis</title>
 <supplementary-material id="source-data-3" content-type="sdata" 
   mimetype="text" mime-subtype="xlsx" xlink:href="source-data-3.xlsx">
  <label>Supplementary File 3</label>
   <title>Representative curves of steady-state kinetic 
    analyses for each IGF1R protein characterized</title>
   <p>Each data point was performed in duplicate and is 
    shown separately.</p>
Related Resources