PukiWiki (named comes from "PHP" + "YukiWiki") is a unique WikiEngine based on the YukiWiki specification created by Mr. Hiroshi Yuki. Mr. sng(ShiNoGi) continued its development until the release of PukiWiki 1.3, and PukiWiki Developers Team inherited the development from him after 1.3.1b.
Information in English : http://pukiwiki.sourceforge.jp/?About%20PukiWiki
Developer's wiki: http://pukiwiki.sourceforge.jp/dev/ (mainly written in Japanese, EUC-JP)
Originally only a Japanese version of the format rule list is available. http://pukiwiki.sourceforge.jp/?%E3%83%98%E3%83%AB%E3%83%97 The page name is HELP in Japanese. However, there is now a (mostly) English version of the rules: http://pukiwiki.sourceforge.jp/index.php?FormatRule