Section 28.10 Footnotes
Footnotes are the farthest thing imaginable from structured authoring. You can put them anywhere, and conceivably they can contain anything. But they do work great in HTML presentations as knowls. However, we do not let the tail wag the dog, and so have to make some compromises for footnotes output in print formats.
As of 2019-01-04 we are fairly restrictive about content. No paragraphs, more like a few sentences, max. If you have more content, consider the
<aside>element, and send feature requests for that.
Many blocks, such as
<remark>, are implemented with the LaTeX
tcolorboxpackage, to make styling and layout much more capable and reliable. But footnotes get trapped within these boxes and render at the end of the box (not the bottom of the page) and have a different scheme for the marks (letters, not numbers). We have mitigated much of this behavior, but the cost is that these footnotes are delayed until the box finishes. So if you have a 4-page example, and use a footnote early, it may appear at the bottom of a page that is 3 or 4 pages away.
Another consequence of the above is that hyperlinks in electronic PDFs, from the mark to the text, need to be disabled (they will never work within a
tcolorbox). Cross-references to a footmark's text will still be active in an electronic PDF.