What is a footnote in an EPUB?
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A footnote is a note printed at the bottom of the page it refers to, linked to the text by a reference mark. In an EPUB there is no page bottom, so the note becomes a linked element that readers can show as a pop-up.
Why it matters when you convert a PDF to EPUB
A PDF draws footnotes as small text at the foot of the page with nothing linking them to the reference. A converter must find each reference mark, match it to its note, move the note out of the running text and link the two with epub:type noteref and footnote, or notes interrupt paragraphs at every page break.
How EpubCC handles it: a block is taken as a footnote when it is smaller than 0.9 times the body text, sits in the bottom half of the page below body text on the same page, and starts with a marker; superscripts in the body with the same label become links to it. The note is written as an EPUB 3 footnote at the end of its chapter.
Related terms
EPUBCheck messages about this
See how EpubCC links footnotes
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