This part of ISO 639 provides a code consisting of language code elements comprising two-letter lan­guage identifiers for the representation of names of languages. The language identifiers according to this part of ISO 639 were devised originally for use in ter­minology, lexicography and linguistics, but may be adopted for any application requiring the expression of language in two-letter coded form, especially in computerized systems. The alpha-2 code was de­vised for practical use for most of the major languages of the world that are not only most frequently repre­sented in the total body of the world’s literature, but which also comprise a considerable volume of spe­cialized languages and terminologies. Additional lan­guage identifiers are created when it becomes apparent that a significant body of documentation written in specialized languages and terminologies exists. Languages designed exclusively for machine use, such as computer-programming languages, are not included in this code.