IETF codes can be much more complex and involve many optional components, potentially leading to effort wasted on whether or not a particular option is necessary. They may have been more stable than ISO 639-3; I do not know if future stability is guaranteed for ISO 639-3.
As a linguistic researcher at the Linguistic Data Consortium UPenn, I work with ISO 639-3 codes every day. They are maintained by the Ethnologue Languages of the World site. Their language name index page is headed Listing of 7413 primary names only. For 41,186 alternate names and dialect names use the site search. Each of those codes specifies a single language -- or sometimes a dialect or group of dialects, since Nature doesn't draw thick sharp lines the way our naming customs pretend she did. Multiple alternate names can be linked to a single code--
Galician A language of Spain ISO 639-3: glg Population 3,170,000 in Spain (1986). Population total all countries: 3,185,000. Region Northwest Spain, Galicia Autonomous Region. Also in Portugal. Language map Portugal and Spain Alternate names Galego, Gallego
and homonymous names can be distinguished by the code:
Romani, Carpathian A language of Czech Republic ISO 639-3: rmc Also spoken in:
Poland Language name Romani, Carpathian Dialects Galician, Transylvanian.
Romania Language name Romani, Carpathian Dialects Galician, Transylvanian.
Furthermore, the ISO 639-3 codes can be extended for dialects and subgroups. The LINGUIST LIST maintains many of the extensions, as well as codes for additional extinct, ancient, historic, and constructed languages.
Language codes
As a linguistic researcher at the Linguistic Data Consortium UPenn, I work with ISO 639-3 codes every day. They are maintained by the Ethnologue Languages of the World site. Their language name index page is headed
Listing of 7413 primary names only.
For 41,186 alternate names and dialect names use the site search.
Each of those codes specifies a single language -- or sometimes a dialect or group of dialects, since Nature doesn't draw thick sharp lines the way our naming customs pretend she did. Multiple alternate names can be linked to a single code--
A language of Spain
ISO 639-3: glg
Population 3,170,000 in Spain (1986). Population total all countries: 3,185,000.
Region Northwest Spain, Galicia Autonomous Region. Also in Portugal.
Language map Portugal and Spain
Alternate names Galego, Gallego
and homonymous names can be distinguished by the code:
A language of Czech Republic
ISO 639-3: rmc
Also spoken in:
Language name Romani, Carpathian
Dialects Galician, Transylvanian.
Language name Romani, Carpathian
Dialects Galician, Transylvanian.
Furthermore, the ISO 639-3 codes can be extended for dialects and subgroups. The LINGUIST LIST maintains many of the extensions, as well as codes for additional extinct, ancient, historic, and constructed languages.