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, among other things: the ISO 639-3 standards for languages include type H, for historical languages, part of a five-way typology to classify languages. Besides the historic languages, there are also ISO 639-3 classifications for living languages, extinct languages, ancient languages, and constructed languages. Old English is an example of a historic 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 their descendant languages: in the example of Old English, Beowulf and other works of Old English literature form a distinct body of material.
