I kinda recall there being some options in old browsers (>10 years ago) where websites could send their privacy policy as a blob in the http header and the brow

I kinda recall there being some options in old browsers (>10 years ago) where websites could send their privacy policy as a blob in the http header and the browser would enable/disable content based on pre-defined user options. However I can't recall the name of this and a quick search isn't showing me anything that rings a bell.