Wrapper element for elements that may be used to group articles into related clusters, e.g., by subject matter or by series. (For intended use, see Remarks below.)
Subject Groupings: For some journals, articles are grouped into categories called subject groupings <subj-group>, and the category is shown in the article’s display or in print. Sometimes the grouping or category refers to the type of article, such as “Essay”, “Commentary”, or “Article”. Sometimes the grouping refers to subject areas, such as “Physical Sciences”, “Biological Sciences”, or “Social Sciences”. Sometimes the grouping refers to topics within one of these larger subject areas, such as “Applied Math”, “Biology”, or “Chemistry”.
In some printed journals, as well as on websites such as the PubMed Central website, articles may be grouped or arranged under these subject headings (here are all the Essays, here are all the Biology articles, etc.).
Some journals divide articles into three layers of grouping, some into two, and some into only one. For example, a one-level grouping might be:
<subj-group> <subject>Retraction</subject> </subj-group>
or, as another example:
<subj-group> <subject>Essay</subject> </subj-group>
And a three-level grouping might be:
<subj-group> <subject>Articles</subject> <subj-group> <subject>Biological Sciences</subject> <subj-group> <subject>Entomology</subject> </subj-group> </subj-group> </subj-group>
Articles may also be assigned to more than one grouping. For example, if an article is classified both as “Biochemistry” under “Biological Sciences” and as “Chemistry” under “Physical Sciences”, the <subj-group> wrapper will repeat to describe both groupings. For example:
<subj-group> <subject>Articles</subject> <subj-group> <subject>Biological Sciences</subject> <subj-group> <subject>Biochemistry</subject> </subj-group> </subj-group> <subj-group> <subject>Physical Sciences</subject> <subj-group> <subject>Chemistry</subject> </subj-group> </subj-group> </subj-group>
<!ELEMENT article-categories (subj-group*, series-title*, series-text?) >
The following, in order:
<article>
<front>
<journal-meta>
...
</journal-meta>
<article-meta>
...
<article-id pub-id-type="pmid">11274384</article-id>
<article-categories>
<subj-group>
<subject>Physical Sciences</subject>
<subj-group>
<subject>Chemistry</subject>
</subj-group>
</subj-group>
<subj-group>
<subject>Biological Sciences</subject>
<subj-group>
<subject>Biophysics</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
...
</title-group>
...
</article-meta>
</front>
<body>
...
</body>
<back>
...
</back>
</article>
articlemeta.ent