I have not seen a comprehensive overview of MediaWiki localisation discussed on the lists I am posting this message to, so I thought I might give it a try. All statistics are based on MediaWiki 1.12 alpha, SVN version r29106.
*Localisation or L10n - the process of adapting the software to be as familiar as possible to a specific locale (in scope)
*Internationalisation or i18n - the process of ensuring that an application is capable of adapting to local requirements (out of scope)
MediaWiki has a user interface (UI) definition for 319 languages. Of those languages at least 17 language codes are duplicates and/or serve a purpose for usability. Reporting on them, however, is not relevant. So MediaWiki in its current state supports 302 languages. To be able to generate statistics on localisation, a MessagesXx.php file should be present in languages/messages. There currently are 262 such files, of which 16 are redirects from the duplicates/usability group. So MediaWiki has an active in-product localisation for 236 languages. 66 languages have an interface, but simply fall back to English.
The MediaWiki core product recognises several collections of localisable content (three of which are defined in messageTypes.inc):
* 'normal' messages that can be localised (1726)
* optional messages that can be localised, which usually only happens for languages not using a Latin script (161)
* ignored messages that should not be localised (100)
* namespace names and namespace aliases (17)
* skin names (7)
* magic words (120)
* special page names (76)
* other (directionality, date formats, separators, book store lists, link trail, and others)
Localisation of MediaWiki revolves around all of the above. Reporting is done on the normal messages only.
MediaWiki is more than just the core product. On http://www.mediawiki.org/wiki/Category:All_extensions some 750 extensions have some kind of documentation. This analysis will scope only to the code currently present in svn.wikimedia.org/svnroot/mediawiki/trunk. The source code repository contains give or take 230 extensions. Of those 230 extensions, about 140 contain messages that can be visible in the UI in some use case (debugging excluded). Out of those 140, about 10 extensions have an exotic implementation for localisation localisation support at all (just English text in the code). 10 extensions appear to be outdated. I have seen about 5 different 'standard' implementations of i18n in extensions. Since MediaWiki 1.11 there is wfLoadExtensionMessages. Not that many extensions use this yet for message handling. If you can help add more standard i18n support for extensions (an overview can be found at http://translatewiki.net/wiki/User:Siebrand/tobeadded) or help in standardising L10n for extensions, please do not hesitate.
==MediaWiki localisation in practice==
Localisation of MediaWiki is currently done in the following ways I am aware of:
* in local wikis: Sysops on local wikis shape and translate messages to fit their needs. This is being done in wikis that are part of Wikimedia, Wikia, Wikitravel, corporate wikis, etc. This type of localisation has the fewest benefits for the core product and extensions because it happens completely out of the scope of svn committers. I have heard Wikia supports languages that are not supported in the svn version. I would like to get some help in identifying and contacting these communities to try and get their localisations in the core product. Together with SPQRobin, I am trying to get what has been localised in local Wikipedias into the core product and recruit users that worked on the localisation to work on a more centralised way of localisation (see Betawiki)
* through bugzilla/svn: A user of MediaWiki submits patches for core messages and/or extensions. These users are mostly part of a wiki community that is part of Wikimedia. These are usually taken care of by committers raymond, rotemliss, and sometimes others). Some users maintain a language directly on SVN. At the moment, 10-15 languages are maintained this way: Danish, German, Persian, Hebrew, Indonesian, Kazach (3 scripts), Chinese (3 variants), and some more less frequently.
* through Betawiki: Betawiki was founded in mid 2005 by Niklas Laxström. In the years to follow, Betawiki has grown to be a MediaWiki localisation community with over 200 users that has contributed to the localisation of 120 languages each month in the past few months. Users that are only familiar with MediaWiki as a tool can localise almost every aspect of MediaWiki (except for the group 'other' mentioned earlier) in a wiki interface. The work of the translators is regularly committed to svn by nikerabbit, and myself. Betawiki also offers a .po export that enables users to use more advanced translation tools to make their translation. This option was added recently and no translations in this format have been sumitted yet. Betawiki also supports translation of 122 extensions, aiming to support everything that can be supported.
==MediaWiki localisation statistics==
MediaWiki localisation statistics have been around since June 2005 at http://www.mediawiki.org/wiki/Localisation_statistics. Traditionally reports have focused on the complete set of core messages. Recently a small study was done after usage of messages, which resulted in a set of almost 500 'most often used messages in MediaWiki', based on usage of messages on the cluster of Wikimedia (http://translatewiki.net/wiki/Most_often_used_messages_in_MediaWiki).
Up to recently there were no statistics available on the localisation of extensions. Through groupStatistics.php in the extension Translate, these statistics can now be created. Aside from reporting on 'most often used MediaWiki messages', 'MediaWiki messages', and 'all extension messages supported by extension Translate' (short: extension messages). Additionally, a meta extension group of 34 extensions used in the projects of Wikimedia has been created (short: Wikimedia messages). A regularly updated table of these statistics can be found at http://translatewiki.net/wiki/Translating:Group_statistics.
Some (arbitrary) milestones have been set for the four above mentioned collections of messages. For the usability of MediaWiki in a particular language, the group 'core-mostused' is the most important. A language must qualify for MediaWiki to have minimal support for that language. Reaching the milestones for the first two groups is something the Wikimedia language committee considers to use as a requirement for new Wikimedia wikis:
* core-mostused (496 messages): 98%
* wikimedia extensions (354 messages): 90%
* core (1726 messages): 90%
* extensions (1785 messages): 65%
Currently the following numbers of languages have passed the above milestones:
* core-mostused: 47 (15,5% of supported languages)
* wikimedia extensions: 10 (3,3% of supported languages)
* core: 49 (16,2% of supported languages)
* extensions: 7 (2,3% of supported languages)
So... Are we doing well on localisation or do we suck? My personal opinion is that we do something in between. Observing that there are some 250 Wikipedias that all use the Wikimedia Commons media repository, and that only 47 languages have a minimal localisation, we could do better. With Single User Login around the corner (isn't it), we must do better. On the other hand, new language projects within Wikimedia all have excellent localisation of the core product. These languages include Asturian, Bikol Central, Lower Sorbian, Extremaduran, and Galician. But where is Hindi, for example, with currently only 7% of core messages translated?
With the Wikimedia Foundation aiming to put MediaWiki to good use in developing countries and products like NGO-in-a-box that include MediaWiki, the potential of MediaWiki as a tool in creating and preserving knowledge in the languages of the world is huge. We have to tap into that potential and *you* (yes, I am glad you read this far and are now reading my appeal) can help. If you know people that are proficient in a language and like contributing to localisation, please point them in the right direction. If you know of organisations that can help localising MediaWiki: please approach them and ask them to help.
We have all the tools now to successfully localise MediaWiki into any of the 7000 or so languages that have been classified in ISO 639-3. We only need one person per language to make it happen. Reaching the first two milestones (core-mostused and wikimedia extensions) takes about 16 hours of work. Using Betawiki or the .po, little to no technical knowledge is required.
This was the pitch. How about we aim to at least double the numbers by the end of 2008 to:
* core-mostused: 120
* wikimedia extensions: 50
* core: 90
* extensions: 20
I would like to wish everyone involved in any aspect of MediaWiki a wonderful 2008.
 older locations are http://www.mediawiki.org/wiki/Localisation_statistics/stats and