* 仕様書

[REFS[
- [2] [CITE@en[Selectors Level 3]] ([TIME[2011-09-29 22:16:17 +09:00]] 版) <http://www.w3.org/TR/selectors/#gen-content>
]REFS]

* 歴史

** CSS2

[REFS[
- [1] [CITE@en[Selectors]] ([TIME[2011-06-07 22:09:52 +09:00]] 版) <http://www.w3.org/TR/CSS2/selector.html#before-and-after>
]REFS]

[3] [CITE@en[CSS3 Generated and Replaced Content Module]]
( ([TIME[2003-05-15 21:54:58 +09:00]] 版))
<http://www.w3.org/TR/2003/WD-css3-content-20030514/#inserting>

[4] [CITE@en[CSS Generated Content Module Level 3]]
( ([TIME[2011-04-21 02:28:30 +09:00]] 版))
<http://dev.w3.org/csswg/css3-content/#inserting-content-into-an-element-the-be>