Some more details are here: http://www.innoq.com/blog/st/2012/03/announcing-roca/

"a set of rules to apply if the goal is to come up with a Web app that is actually on the Web as opposed to be tunnelled through the Web. We tried to come up with a catchy name, and finally arrived at ”ROCA”, a conveniently pronouncable acronym for “Resource-oriented client architecture”.

So rather than a manifesto, they're trying to devise a nomenclature, along the lines of how Ajax gave a name to non-page refresh server communication with the browser.

Please no :-) I'm really through with manifestos of any kind.