Luokitus perustuu ISO 639-1 -standardiin (Codes for the representation of names of languages, Part 1: Alpha-2 code, 15.7.2002). Standardi koostuu kielten nimistä ja niille annetuista kaksikirjaimisista koodeista. Se korvaa vuonna 1988 ilmestyneen ISO 639 -standardin. ISO 639-1 -standardia ylläpitää Infoterm (International Information Centre for Terminology). Tunnusjärjestelmään kuuluvat kielten kaksikirjaimiset tunnukset kirjoitetaan pienaakkosin. Tunnukset muodostetaan kunkin kielen omakielisen nimen pohjalta. Poikkeuksena ovat japanin, suomen ja unkarin kielet, joiden tunnukset on muodostettu näiden maiden toivomuksen mukaisesti englanninkielisen nimen pohjalta. Viimeisin koodisto on vuodelta 2010. Koodistoa käytetään koulutustarjonnan lukion kielivalikoimassa ja henkilötiedonsiirroissa. Koodistoon on lisätty muutama koodi joita tarvitaan Opintopolussa. Näitä on vk=viittomakieli (koodi merkitty lakkautuneeksi), 98=ei virallinen kieli ja 99=tuntematon Koodistoon liittyvät tiedustelut yhteisetpalvelut@opintopolku.fi Opetushallitus varaa oikeuden muuttaa Opintopolun koodistoja, niissä olevia koodeja sekä niiden selitteitä ja kuvauksia Koodistoa käyttää mm. KOSKi-palvelu
| Koodiarvo | Lyhytnimi | Nimi | Kuvaus |
|---|---|---|---|
| 98 | Non-official language | Non-official language | Non-official language |
| 99 | Other | Other | Other |
| AA | Afar | Afar | Afar |
| AB | Abkhazian | Abkhazian | Abkhazian |
| AE | Avestan | Avestan | Avestan |
| AF | Afrikaans | Afrikaans | Afrikaans |
| AK | Akan | Akan | Akan |
| AM | Amharic | Amharic | Amharic |
| AN | Aragonese | Aragonese | Aragonese |
| AR | Arabic | Arabic | Arabic |
| AS | Assamese | Assamese | Assamese |
| AV | Avar, Avarish | Avar, Avarish | Avar, Avarish |
| AY | Aymara | Aymara | Aymara |
| AZ | Azerbaijani | Azerbaijani | azeri, aiemmin myös: azerbaidžani |
| BA | Bashkir | Bashkir | Bashkir |
| BE | Belarusian | Belarusian | Belarusian |
| BG | Bulgarian | Bulgarian | Bulgarian |
| BH | Bihari | Bihari | biharikieli, aiemmin: bihari |
| BI | Bislama | Bislama | Bislama |
| BM | Bambara | Bambara | Bambara |
| BN | Bengali, Bangla | Bengali, Bangla | Bengali, Bangla |
| BO | Tibetan | Tibetan | Tibetan |
| BR | Breton | Breton | Breton |
| BS | Bosnian | Bosnian | Bosnian |
| CA | Catalan | Catalan | Catalan |
| CE | Chechen | Chechen | Chechen |
| CH | Chamorro | Chamorro | Chamorro |
| CO | Corsican | Corsican | Corsican |
| CR | Cree | Cree | Cree |
| CS | Czech | Czech | Czech |
| CU | Old Slavonic | Old Slavonic | Old Slavonic |
| CV | Chuvash | Chuvash | Chuvash |
| CY | Welsh | Welsh | kymri, aiemmin myös: wales |
| DA | Danish | Danish | Danish |
| DE | German | German | German |
| DV | Divehi; Maldivian | Divehi; Maldivian | Divehi; Maldivian |
| DZ | Dzongkha; Bhutani; Butanese | Dzongkha; Bhutani; Butanese | dzongkha, aiemmin myös: bhutani |
| EE | Ewe | Ewe | Ewe |
| EL | Greek, Modern | Greek, Modern | Modern Greek |
| EN | English | English | English |
| EO | Esperanto | Esperanto | Esperanto |
| ES | Spanish, Castilian | Spanish, Castilian | Spanish, Castilian |
| ET | Estonian | Estonian | viro, aiemmin myös: eesti |
| EU | Basque | Basque | Basque |
| FA | Persian, Farsi | Persian, Farsi | Persian, Farsi |
| FF | Fulah; Fula; Fulani; Fulfulde; Peul | Fulah; Fula; Fulani; Fulfulde; Peul | fulani, aiemmin myös: fulfulde |
| FI | Finnish | Finnish | Finnish |
| FJ | Fijian | Fijian | Fijian |
| FO | Faroese; Faeroese | Faroese; Faeroese | Faroese; Faeroese |
| FR | French | French | French |
| FY | Frisian | Frisian | länsifriisi, aiemmin: friisi |
| GA | Irish | Irish | Irish |
| GD | Gaelic, Scottish Gaelic | Gaelic, Scottish Gaelic | Gaelic, Scottish Gaelic |
| GG | Guernesiais | Guernesiais | Guernesiais |
| GL | Galician; Gallegan | Galician; Gallegan | Galician; Gallegan |
| GN | Guarani | Guarani | Guarani |
| GU | Gujarati | Gujarati | Gujarati |
| GV | Manx | Manx | Manx |
| HA | Hausa | Hausa | Hausa |
| HE | Hebrew | Hebrew | Hebrew |
| HI | Hindi | Hindi | Hindi |
| HO | Hiri Motu | Hiri Motu | Hiri Motu |
| HR | Croatian | Croatian | Croatian |
| HT | Haitian, Haitian Creole | Haitian, Haitian Creole | Haitian, Haitian Creole |
| HU | Hungarian | Hungarian | Hungarian |
| HY | Armenian | Armenian | Armenian |
| HZ | Herero | Herero | Herero |
| IA | Interlingua | Interlingua | Interlingua |
| ID | Indonesian | Indonesian | indonesia, aiemmin myös: bahasa indonesia |
| IE | Interlingua | Interlingua | Interlingua |
| IG | Igbo | Igbo | igbo, aiemmin myös: ibo |
| II | Sichuan Yi | Sichuan Yi | Sichuan Yi |
| IK | Inupiaq | Inupiaq | Inupiaq |
| IM | - | - | - |
| IO | Ido | Ido | Ido |
| IS | Icelandic | Icelandic | Icelandic |
| IT | Italian | Italian | Italian |
| IU | Inuktitut | Inuktitut | Inuktitut |
| IW | - | Heprea (vanha) | - |
| JA | Japanese | Japanese | Japanese |
| JE | Jerriais | Jerriais | Jerriais |
| JV | Javanese | Javanese | Javanese |
| KA | Georgian | Georgian | georgia; aiemmin myös: gruusia |
| KE | Karjala | Karjala | Karjala |
| KG | Kongo | Kongo | kongo, aiemmin myös: kikongo |
| KI | Kikuyu, Gikuyu | Kikuyu, Gikuyu | Kikuyu, Gikuyu |
| KJ | Kwanyama, Kuanyama | Kwanyama, Kuanyama | kuanjama, aiemmin myös: kwanjama |
| KK | Kazakh | Kazakh | Kazakh |
| KL | Greenlandic, Kalaallisut | Greenlandic, Kalaallisut | Greenlandic, Kalaallisut |
| KM | Cambodian, Khmer | Cambodian, Khmer | keskikhmer, aiemmin: khmer, kambodža |
| KN | Kannada | Kannada | Kannada |
| KO | Korean | Korean | Korean |
| KR | Kanuri | Kanuri | Kanuri |
| KS | Kashmiri | Kashmiri | Kashmiri |
| KU | Kurdish | Kurdish | Kurdish |
| KV | Komi | Komi | Komi |
| KW | Cornish | Cornish | Cornish |
| KY | Kirghiz, Kyrgyz | Kirghiz, Kyrgyz | Kirghiz, Kyrgyz |
| LA | Latin | Latin | Latin |
| LB | Luxembourgish | Luxembourgish | Luxembourgish |
| LG | Ganda; Luganda | Ganda; Luganda | ganda, aiemmin myös: luganda |
| LI | Limburgan, Limburger | Limburgan, Limburger | Limburgan, Limburger |
| LN | Lingala | Lingala | Lingala |
| LO | Laotian, Lao | Laotian, Lao | Laotian, Lao |
| LT | Lithuanian | Lithuanian | Lithuanian |
| LU | Luba-Katanga | Luba-Katanga | katanganluba, aiemmin myös: luba |
| LV | Latvian | Latvian | latvia, aiemmin myös: lätti |
| MG | Malagasy | Malagasy | malagasi, aiemmin myös: madagassi |
| MH | Marshallese | Marshallese | Marshallese |
| MI | Maori | Maori | Maori |
| MK | Macedonian | Macedonian | Macedonian |
| ML | Malayalam | Malayalam | Malayalam |
| MN | Mongolian | Mongolian | Mongolian |
| MO | Moldavian | Moldavian | moldova, aiemmin: moldavia |
| MR | Marathi | Marathi | Marathi |
| MS | Malay | Malay | Malay |
| MT | Maltese | Maltese | Maltese |
| MY | Burmese, Myanmar | Burmese, Myanmar | Burmese, Myanmar |
| NA | Nauruan | Nauruan | Nauruan |
| NB | Norwegian Bokmål | Norwegian Bokmål | norjan bokmål, aiemmin myös: kirjanorja |
| ND | North Ndebele | North Ndebele | North Ndebele |
| NE | Nepali | Nepali | Nepali |
| NG | Ndonga | Ndonga | Ndonga |
| NL | Dutch | Dutch | Dutch |
| NN | Norwegian Nynorsk | Norwegian Nynorsk | norjan nynorsk, aiemmin myös: uusnorja |
| NO | Norwegian | Norwegian | Norwegian |
| NR | South Ndebele | South Ndebele | South Ndebele |
| NV | Navajo, Navaho | Navajo, Navaho | Navajo, Navaho |
| NY | Chichewa, Cheva, Nyanja | Chichewa, Cheva, Nyanja | Chichewa, Cheva, Nyanja |
| OC | Occitan, Provencal | Occitan, Provencal | Occitan, Provencal |
| OJ | Ojibwa | Ojibwa | Ojibwa |
| OM | Afan Oromo; Oromo | Afan Oromo; Oromo | oromo, aiemmin myös: afan oromo |
| OR | Oriya | Oriya | Oriya |
| OS | Ossetian, Ossetic | Ossetian, Ossetic | Ossetian, Ossetic |
| PA | Punjabi, Panjabi | Punjabi, Panjabi | Punjabi, Panjabi |
| PI | Pali | Paali | Pali |
| PL | Polish | Polish | Polish |
| PS | Pashto, Pushto | Pashto, Pushto | paštu, myös: afgaani |
| PT | Portuguese | Portuguese | Portuguese |
| QU | Quechua | Quechua | Quechua |
| RI | Romani | Romani | Romani |
| RM | Rhaeto-Romance | Rhaeto-Romance | Rhaeto-Romance |
| RN | Kirundi; Rundi | Kirundi; Rundi | rundi, aiemmin myös: kirundi |
| RO | Romanian | Romanian | Romanian |
| RU | Russian | Russian | Russian |
| RW | Kinyarwanda, Rwanda | Kinyarwanda, Rwanda | ruanda, aiemmin myös: kinjaruanda, njaruanda |
| SA | Sanskrit | Sanskrit | Sanskrit |
| SC | Sardinian | Sardinian | Sardinian |
| SD | Sindhi | Sindhi | Sindhi |
| SE | Northern Sami | Northern Sami | Northern Sami |
| SG | Sango, Sangho | Sango, Sangho | Sango, Sangho |
| SH | Serbo-Croatian | Serbo-Croatian | Serbo-Croatian |
| SI | Sinhala; Sinhalese; Singhalese | Sinhala; Sinhalese; Singhalese | sinhala, aiemmin: singali |
| SK | Slovak | Slovak | Slovak |
| SL | Slovenian | Slovenian | Slovenian |
| SM | Samoan | Samoan | Samoan |
| SN | Shona | Shona | šona, aiemmin: shona |
| SO | Somali | Somali | Somali |
| SQ | Albanian | Albanian | Albanian |
| SR | Serbian | Serbian | Serbian |
| SS | Siswati, Swazi, Swati | Siswati, Swazi, Swati | swazi, aiemmin myös: siswati |
| ST | Sesotho, Southern Sotho | Sesotho, Southern Sotho | Sesotho, Southern Sotho |
| SU | Sundanese | Sundanese | Sundanese |
| SV | Swedish | Swedish | Swedish |
| SW | Swahili, Kiswahili | Swahili, Kiswahili | swahili, aiemmin myös: suahili |
| TA | Tamil | Tamil | Tamil |
| TE | Telegu | Telegu | Telegu |
| TG | Tajiki | Tajiki | Tajiki |
| TH | Thai | Thai | Thai |
| TI | Tigrinya | Tigrinya | Tigrinya |
| TK | Turkmen | Turkmen | Turkmen |
| TL | Tagalog | Tagalog | tagalog, aiemmin myös: pilipino |
| TN | Setswana, Tswana | Setswana, Tswana | Setswana, Tswana |
| TO | Tongan (Tonga Islands) | Tongan (Tonga Islands) | Tongan (Tonga Islands) |
| TR | Turkish | Turkish | Turkish |
| TS | Tsonga | Tsonga | Tsonga |
| TT | Tatar | Tatar | Tatar |
| TW | Twi | Twi | Twi |
| TY | Tahitian | Tahitian | Tahitian |
| UG | Uighur | Uighur | Uighur |
| UK | Ukrainian | Ukrainian | Ukrainian |
| UR | Urdu | Urdu | Urdu |
| UZ | Uzbek | Uzbek | Uzbek |
| VE | Venda | Venda | Venda |
| VI | Vietnamese | Vietnamese | Vietnamese |
| VK | Sign language | Sign language | Sign language |
| VO | Volapük | Volapük | Volapük |
| WA | Walloon | Walloon | Walloon |
| WO | Wolof | Wolof | Wolof |
| XH | Xhosa | Xhosa | Xhosa |
| XX | Other languages | Other languages | Other languages |
| YI | Yiddish | Yiddish | jiddiš, aiemmin myös: jiddi |
| YO | Yoruba | Yoruba | Yoruba |
| ZA | Zhuang, Chuang | Zhuang, Chuang | zhuang |
| ZH | Chinese | Chinese | Chinese |
| ZU | Zulu | Zulu | Zulu |