footnote

A short piece of text, often numbered, placed at the bottom of a printed page, that adds a comment, citation, reference etc, to a designated part of the main text.

consult the footnotes for more details

Above all, the 48-page timetables of the new service, which have been distributed free at every station in the scheme, are a model to the rest of B.R. For the first time on British Railways, so far as we are aware, a substantial timetable has been produced, not only without a single footnote but also devoid of all wearisome asterisks, stars, letter suffixes and other hieroglyphics.

An event of lesser importance than some larger event to which it is related.

a mere footnote in history

If we are another footnote to Plato, Plato was himself already a footnote to still earlier footnotes, in an endless chain of footnotes to footnotes

A qualification to the import of something.

To add footnotes to a text.

She does everything she does with a kind of terrifying thoroughness, footnoted and bibliographied, as it were, down to the smallest detail.