Sina Weibo updates its "Community Conventions"
Of special note is article 13:
Article 13: Users have the right to publish information, but may not publish any information that:
Opposes the basic principles established by the constitution
Harms the unity, sovereignty, or territorial integrity of the nation
Reveals national secrets, endangers national security, or threatens the the honor or interests of the nation
Incites ethnic hatred or ethnic discrimination, undermines ethnic unity, or harms ethnic traditions and customs
Promotes evil teachings and superstitions
Spreads rumors, disrupts social order, and destroys societal stability
Promotes illicit activity, gambling, violence, or calls for the committing of crimes
Calls for disruption of social order through illegal gatherings, formation of organizations, protests, demonstrations, mass gatherings and assemblies
Has other content which is forbidden by laws, administrative regulations and national regulations.
(Via Caijing English, via China Digital Times)