As a responsible webmaster I want to mark some of my content as unsuitable for certain age groups, there's nothing illegal or pornographic but it does feature bad language and violence that might be unsuitable for children, mostly in images so a text parser won't pick it up. Is there a standard that internet filtering software will recognise?
Obviously, I appreciate that nothing is going to stop children viewing the content if they are just using a vanilla browser on an open connection but if there is a content rating standard then I'd like to use it to help those able to honour it.