 Normally, the term "Proto-X" refers to the last common ancestor of a group of languages, occasionally attested but most commonly reconstructed through the comparative method, as with Proto-Indo-European and Proto-Germanic.An earlier stage of a single language X, reconstructed through the method of internal reconstruction, is termed "Pre-X", as in Pre-Old Japanese.It is also possible to apply internal reconstruction to a proto-language, obtaining a pre-proto-language, such as Pre-Proto-Indo-European.