Merge the following from the English version:
1.13 -> 1.20 basics/chapter.sgml
Submitted by: Shun SUZUKI <si006@ccm.gs.niigata-u.ac.jp>,
Ryusuke Suzuki <ryusuke@nucl.sci.hokudai.ac.jp>, Hiroki Sato <hrs@geocities.co.jp>
Reviewed by: Hiroki Sato <hrs@geocities.co.jp>
References: [doc-jp 7273,7428,7431,7432,7436,7447]