Ruthenian language
The "prevailing" language of the documents of the 15th and the most of the 16th century Metrica had been the Ruthenian language. Alternatively, the prevailing use of the Ruthenian language in the Metrica is extended up to the mid-17th century. The documents, concerned with the Western Europe, had been issued in Latin, occasionally in German. The documents, concerned with the Roman Catholic Church, had been issued in Latin. See also naming of the Ruthenian language.