I was trying to search for PCT publications in Chinese, Japanese and Korean. When I used CN, JP and KR as the search term I got ZERO hits! I looked in vain for a list of the language abbreviations. The help screen which gave an example of "JA or EN" gave me a hint that WIPO was using its own abbreviations. So I tried "KO" for Korean and that worked. I then tried "CH" for Chinese. Nothing! Searching around the web via Google I finally found some reference (not from WIPO!) that related "ZH" to Chinese.
It would be nice if WIPO had a link to a list of language search terms right from the searching screen!
51. The lang attribute normally contains a two-letter code based on ISO standards for the language of the content of the element to which it is attached. In cases where the two-letter code is not adequate, offices are encouraged to follow the conventions established by the Internet Engineering Task Force and described in Tags for the Identification of Languages(