Material published with an article but following the narrative flow.
The following, in order:
<label> Label (of an Equation, Figure, Reference, etc.), zero or one
<title> Title, zero or more
Any combination of:
<ack> Acknowledgments
<app-group> Appendix Group
<bio> Biography
<fn-group> Footnote Group
<glossary> Glossary Elements List
<ref-list> Reference List (Bibliographic)
<notes> Notes
<sec> Section