http://www.w3.org/News/2008#item175 says:

Participants from four W3C Groups -- CSS, Internationalization Core, SVG and XSL Working Groups -- as part of the Japanese Layout Task Force published an update of Requirements of Japanese Text Layout. This document describes requirements for general Japanese layout realized with technologies like CSS, SVG and XSL-FO. The document is mainly based on a standard for Japanese layout, JIS X 4051. However, it also addresses areas which are not covered by JIS X 4051. This draft contains most of the material which the task force intends to publish as a Group Note in December 2008. A Japanese version is also available. Learn more about W3C's Internationalization Activity.