@soller but all this should be voluntary and for the client to decide.
If the client sends a certain content restriction, then the server may opt to avoid sending such content. On the other hand, if the server sends a certain content type, the client can opt to not show it.
It should be illegal to send a wrong content type though. That is, if you don't want to care about the content types of your website, then just don't annotate, but don't claim that it's suitable for all audiences.