Anarchopedia is using ISO 639-2 (three letters) codes from its beginning. Two letters codes are generally Apache config hack for compatibility with Wikipedia (interwiki links also have compatibility with Wikipedia and they are usually used, even three letters codes should be used). Long time ago I asked Andre Engels how to change that, but I forgot how to do that. So, may someone fix it? Here is the list of the pairs:
ar:ara id:ind bs:bos zh:chi da:dan de:deu el:ell es:spa eo:epo fr:fra hr:hrv it:ita ja:jpn lt:lit nl:dut no:nor nn:nno pl:pol pt:por ro:rum ru:rus sr:srp sh:nsh sv:swe
(nsh is not an ISO 639-2 code)