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Section 22.3 Footnotes and asides

Footnotes are not too hard, just use <fn>, but note that for the time being, what can go inside a footnote is very, very restricted. 1  For instance, you can't put a <p> (and thus you can't put lists) inside a footnote. Also, no displayed math via <me>. There's a lot of care being taken because of the prospect of footnotes inside footnotes inside footnotes.

This is a sample footnote, just so you can see how one looks.

Because of the restrictions on footnotes, it is important to keep them short. A good alternative for longer things that are somewhat digressional is the aside, which comes in three flavors: <aside>, <biographical>, <historical>. Each of these allows an optional title and then a variety of tags such as <p>, <figure>, and <sidebyside> (and many more).

  <title>A Sample Aside</title>
    Here is some text inside a sample aside.
    I'm going to put the Pythagorean identity below:
      \sin^2(x) + \cos^2(x) = 1

    This aside has two paragraphs.
    You can't do that with a footnote.
Listing 22.3.1. A sample <aside>

The code in Listing 22.3.1 produces the aside “A Sample Aside”. A less contrived example of an aside can be found in Section 19.4.