I always took footnotes for granted. You need them as you’re writing, you insert an indicator at the right place and it points the reader to an amplification, a citation, an off-hand comment, or something — but it’s out of the way, a distraction to the point you’re trying to make.
Some documents don’t need them, but some require them (e.g., scholarly documents, legal documents). In those documents, the footnotes contain such important information that, as Barry Bealer suggests in When footnotes are the content, “the meat [is] in the footnotes.”
The web doesn’t make it easy to represent footnotes. Footnotes on the Web argues that HTML is barely up to the task of presenting footnotes in any effective form.
But if you were to recreate the whole thing from scratch, without static paper as a model, how would you model footnotes?
In a document, a footnote is composed of two pieces of related information. One is the point that you’re trying to make, typically a new point. The other is some pre-existing reference material that presumably supports your point. If it is always the new material that points at the existing, supporting material, then we’re building an information taxonomy bottom up — with the unfortunate property that entering at higher levels will prevent us from seeing lower levels through explicitly-stated links.
To be fair, there are good reasons for connections to be bidirectional. Unidirectional links are forgivable for the paper model, with its inherently temporal life. But the WWW is more malleable, and bidirectional links don’t have to be published at the same time as the first end of the link. In this sense, HTML’s linking mechanism, the ‘<a href=”over_there”>’ construct is fundamentally broken. Google’s founders exploited just this characteristic of the web to build their company on a solution to a problem that needn’t have been.
And people who have lived through the markup revolution from the days of SGML and HyTime know that it shouldn’t have been.
But footnotes still only point bottom up. Fifteen to twenty years on, many of the deeper concepts of the markup revolution are still waiting to flower.