[1] Emacs-w3 User's Manual - Supported Markup Languages (1996-01-22 06:02:45 +09:00 版) <http://www.informatik.uni-hamburg.de/RZ/software/emacs/w3/w3_2.html#SEC6>
[2] W3C XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes ( (2012-04-05 06:34:51 +09:00 版)) <http://www.w3.org/TR/2012/REC-xmlschema11-2-20120405/#ENTITY>