I think everybody has experience of websites with footnotes linked to . Moreover, it is a practice also ratified by HTML spec to use
<a> elements to connect following occurrances to the explanatory text, together with
<dfn> elements for term definition.
Wouldn’t it be useful to have
rel keywords for such cases? Something like
<a rel="dfn"> and
<a rel="note">; there could also be only one keyword, but notice that these cases are different both as markup and as concept (a note can be a source or a reference, rather than a definition). This could be used for scripts creating a rollover note expansion (e.g. Wikipedia) other than anchor recalling (vendors could also take into account implementing native solutions for it, eventually).
Hope to receive feedback.
EDIT: I consulted Existing rel values page on Microformats wiki, and “footnote” keyword is present in both “POSH usage” and “Dropped” sections. Maybe “footnote” was used as marker for the expansion in some websites and as marker for text occurrances in other places.
I think this issue deserves a standard once and for all (and of course this standard won’t be “footnote”…)