The Appendix Probi ("Probus' Appendix") is the conventional name for a series of five documents believed to have been copied in the seventh or eighth century in Bobbio, Italy. Its name derives from the fact that the documents were found attached to a copy of the Instituta Artium, a treatise named after (but probably not written by) the first-century grammarian Marcus Valerius Probus.The Appendix was likely composed in Rome around the first half of the fourth century AD.It is specifically the third of the five documents that has attracted scholarly attention, as it contains a list of 227 spelling mistakes, along with their corrections, which shed light on the phonological and grammatical changes that the local vernacular was experiencing in the early stages of its development into Romance. The text survives only in a carelessly transcribed water-damaged manuscript of the 7th or 8th century which is kept at the Biblioteca Nazionale Vittorio Emanuele III as MS Lat. 1 (formerly Vindobonensis 17). Source: Wikipedia (en)