[REFS[
- [1] [CITE[TrackBack Technical Specification]] ([TIME[2014-05-23 03:49:17 +09:00]] 版) <http://web.archive.org/web/20090208054135/http://sixapart.com/pronet/docs/trackback_spec#Auto-Discovery_of_TrackBack_Ping_URLs>
]REFS]