If you Google "Javadoc Tag Specification" the results are sad, and the fault is not entirely on Google.

We have no clear specification doc or page for "Javadoc tags". The best I can find is within the general tool documentation for the javadoc tool itself, such as here:
https://docs.oracle.com/javase/7/docs/technotes/tools/solaris/javadoc.html#javadoctags

but it is not listed, for example, from this page on Javadoc Technology
https://docs.oracle.com/javase/8/docs/technotes/guides/javadoc/index.html
which is the page you get to when you click on "javadoc" in the top-level "Brick Wall" page for JDK 8
https://docs.oracle.com/javase/8/docs/

The info is also available within this page, but I could not discern an explicit link to the appropriate section of the file:
https://docs.oracle.com/javase/8/docs/technotes/tools/unix/javadoc.html


Generally, we should revisit the structure of the documentation to separate that which is more like a specification of doc comments and tags from the text which is more man-page like, giving a description of the tool, its options, and how it works.