[1] CSS3 Generated and Replaced Content Module ( ( 版)) <http://www.w3.org/TR/2003/WD-css3-content-20030514/#counters>
[2] CSS Generated Content Module Level 3 ( ( 版)) <http://dev.w3.org/csswg/css3-content/#counters>
[3] CSS Generated Content Module Level 3 ( ( 版)) <http://dev.w3.org/csswg/css3-content/#counters>