Historical language
Historical languages are languages that were spoken in a historical period, but that are distinct from their modern form; that is, they are forms of languages historically attested to from the past which have evolved into more modern forms. Thus, historical languages contrast with dead languages. Also, historical languages contrast with reconstructed languages of theoretical linguistics. One of the approaches to defining and using the concept of historical languages is implemented in the ISO 639 standards.
ISO 639
The International Organization for Standardization maintains and publishes standards for languages, amongst other things. The ISO 639-3 standards for languages include a five-way typology to classify languages, including type H for historical languages. Besides historical languages, there are also ISO 639-3 classifications for: living languages ; extinct languages ; ancient languages ; and constructed languages.Old English is an example of an historical language. The ISO 639 language code for Old English is
ang. A further ISO 639-3 criterion for historic languages is that they have a distinct literature from that of their descendant languages: in the example of Old English, Beowulf and other works of Old English literature form a body of material that is distinct from the broader corpus of English literature.