Some article types, such as corrigenda, errata, and retractions, are related to another article.
The Related_Article paragraph style is applied to a paragraph formatted like a bibliographic reference, giving the details of the article that is being corrected or retracted.
Letters to the Editor also generally refer to another article, but they are often published together, and they are set up differently.
The Related_Article paragraph is restructured to your editorial style by Bibliographic Processing, and links to PubMed and Crossref can be added by the respective Advanced Processes, if available.
The type of relationship between the current article and the related article is set in the Related Article dropdown on the Document Information dialog, and this feeds directly into the @related-article-type attribute in the XML. The JATS XML Tag Library notes: