Athletes at the London Olympics will be allowed to blog and post on Twitter but could be thrown out if their musings breach guidelines.
Competitors may write only "first-person, diary-type" entries but should not act as reporters.
All social media activity must respect the Olympic Charter, which bans political demonstrations.... postings must be dignified and in good taste and not contain vulgar or obscene words or images.
Dozens of athletes blogged during the last Olympics in Beijing in 2008, when Twitter was still a reasonably new phenomena, but the uploading of videos was banned and pictures restricted to prevent copyright infringements.
Still photographs taken at venues, largely banned in Beijing, may now be uploaded to social media sites but not sold or "otherwise" distributed.