Twitter is clamping down on graphic sexual activities and provocative nudity that people post on quick clip video app Vine, making it clear that explicit sexual content is unwanted.
Twitter produced a support article to lay out what explicit material includes: various depictions of sex acts (human or animated), nudity that is sexually provocative or in a sexual context, and graphic depictions of sexual arousal.
The firm revealed the updates in a blog post.
"We introduced Vine to make it easier for people to find, watch, create and share videos right from their mobile phones. As we've watched the community and your creativity grow and evolve, we've found that there's a very small percentage of videos that are not a good fit for our community. So we're making an update to our Rules and Terms of Service to prohibit explicit sexual content," it said.
"For more than 99 percent of our users, this doesn't really change anything. For the rest: we don't have a problem with explicit sexual content on the internet - we just prefer not to be the source of it."
So what isn't explicit sexual content? Documentaries with nudity, breast feeding, artistic nudity, and clothed, but rather sexy dancing, are all OK.
Vine was not around very long before it had its first pornography scandal. In January last year a collection of hardcore clips was selected as an Editor's Choice... briefly.