Appears in
Frequency
<front>
Once
Have the Document metadata, which basic elements are:
Tag
<article-id>
<article-categories>
<title-group>
<contrib-group>
<aff>
<author-notes>
<pub-date>
<volume>
<issue>
<fpage>, <lpage> or <elocation-id>
<abstract>, <trans-abstract>
<kwd-group>
<history>
<permissions>
<counts>
<funding-group>
Note
Have in mind that not all tags listed above are mandatory, check the documentation of each one of them to see its frequency of use.