Within a bibliographic reference (<mixed-citation> or <element-citation> and similar elements), the <source> element names the title of the resource being referenced (the top-most title in the citation). For example, a <source> element might contain:

• the name of a journal;
• a book title;
• the name of podcast;
• a report title;
• a conference proceedings title;
• the name of a audio, television, radio, or streaming program;
• the name of a software product (“Oxygen Editor”, “Microsoft Excel”);
• the “name” of a website;
• for data citations, the name of the top-hierarchical level of a data repository; or
• the name or title of any resource being cited (patent, standard, thesis, working paper, etc.).

The element <trans-source> names the resource when the resource title has been translated into a language other than that in which it was originally published. For example, if a book’s was originally published in French, the <source> element would contain the French title, and a <trans-source> element might contain the equivalent English or German book title.

The hierarchical level just below the resource (which names the part of the resource being cited, for example, the title of the article within the journal) is tagged differently depending on the type or resource being cited.

For example:

• For journal citations, the <source> is the name of the journal and the title of the article being cited is <article-title>.
• For preprint citations, the title of the preprint is <article-title>.
• For book citations, the <source> is the name of the book and the title of the book chapter, module, lesson, part, or other-named book division that is being cited is a <part-title>. (Note: the deprecated element <chapter-title> was used for this in past versions of JATS.)
• For citing a specific episode or similar of a podcast, streaming show, radio broadcast, cable show, television news, etc., the name of the show, podcast, etc. is the <source> and a <part-title> names the episode cited. For example: <part-title>The Beetle Whisperer</part-title>, <source>All Thing Considered</source>.
• For citing data sources, the name of the data repository is usually tagged as a <source>, but it may also be tagged as a <data-title>. A data citation may use as many <data-title> elements as necessary to name the multiple levels of a hierarchical data source.
• For citing a standalone audio/video/multimedia/podcast, the “title” of the work will typically be thought of as the <source> rather than as any of the title elements, e.g., <source>How to build and fire a mini-cannon</source>. If the audio/video/multimedia/podcast is part of a series, the series name should be the <source> and the episode title should be a <part-title>.
• For citing a video within a journal, if the citation type is “video”, the journal name would be the <source> and the title of the video would be tagged as a <part-title>.

In summary, the title elements allowed in current citations are: