[1] Web Controls 1.0 (2004-11-09 08:49:52 +09:00 版) <http://www.whatwg.org/specs/web-controls/current-work/#user-focus-select-unknown>
[2] Web Controls 1.0 ( (2004-11-09 08:49:52 +09:00 版)) <http://www.whatwg.org/specs/web-controls/current-work/#focus0>