Most Wikimedia Foundation (WMF) wiki projects have equivalent editions for different languages, with web addresses in the format: [language code].[WMF project name].org. Each language is usually represented by a ISO 639-1 or ISO 639-3 code. For example, the code for English is en, then en.wiktionary.org is the English Wiktionary and en.wikipedia.org is the English Wikipedia. Similarly, the code for French is fr, then fr.wiktionary.org is the French Wiktionary and fr.wikipedia.org is the French Wikipedia.
However, not all languages are coded by ISO. When new language editions of Wikimedia projects are introduced and there are no ISO codes for them, WMF Language Committee creates their own language codes.
The full list of Wiktionaries can be found at meta:Wiktionary and the list of existing active Wikimedia codes not coded by ISO can be found at the following table:
|Wikimedia code||ISO codes||Language name||Comments|
|bat-smg||sgs||Samogitian||Language now given ISO code.|
|be-x-old||be||Belarusian (Tarashkevitsa)||IANA language tag be-tarask|
|cbk-zam||cbk||Zamboanga Chavacano||Wikimedia code does not conform to pattern, could have been cbk-x-zam. cbk is the ISO code of Chavacano proper, which Wiktionary treats Zamboanga as a dialect of.|
|eml||egl, rgn||Emilian-Romagnol||Emilian-Romagnol ISO 639-3 code eml now retired and split into Emilian egl and Romagnol rgn.|
|fiu-vro||vro||Võro||Language now given ISO code.|
|ksh||-||Ripuarian||ISO assigns ksh to Kölsch language instead.|
|map-bms||-||Banyumasan||Wikimedia code does not conform to pattern, could have been map-x-bms.|
|nds-nl||nds-nl||Dutch Low Saxon||The Plattdüütsch projects use nds, but nds-nl is a standard-conforming code for the orthographic variant used in the Netherlands, distinct from the variant used in Lower Saxony, Germany; just like pt-br is a standard variant of pt.|
|nrm||nrf||Norman||ISO assigns nrm to Narom language instead, could have been roa-x-nrm, or probably better with fr-x-nrm or even nrf. nrf is the code of the Guernésiais and Jèrriais dialects of Norman; Wiktionary uses it for all dialects.|
|roa-rup||rup||Aromanian||Language now also ISO coded.|
|roa-tara||-||Tarantino||Wikimedia code does not conform to pattern, could have been it-x-tara.|
|sh||hbs||Serbo-Croatian||Serbo-Croatian ISO 639-1 code sh now retired.|
|simple||-||Simple English||Wikimedia code does not conform to pattern, could have been en-simple (if registered) or en-x-simple for now.|
|zh-classical||lzh||Literary Chinese||Language now also ISO coded.|
|zh-min-nan||nan||Min Nan||IETF extension, now also ISO coded.|
|zh-yue||yue||Cantonese||IETF extension, now also ISO coded.|
Note: This list should not be confused with the list of languages that are used in the English Wiktionary but are not represented by individual ISO 639-1 or ISO 639-3 codes. See Wiktionary:Languages without ISO codes#List of exceptions.