The opening words of the second folio of a manuscript. Since these words differ from one copy of a text to another, depending on the size of the script and folio, the secundo folio is often cited when cataloguing manuscripts, a practice that originated in the Middle Ages in order to distinguish individual copies of a text in a way that its opening words could not. May be abbreviated to 'sec. fol.' or '2o fo'.
íncipit, éxplicit de referencia
Michelle Brown, Understanding Illuminated Manuscripts (Malibu, CA: J. Paul Getty Museum in association with the British Library, c1994).