I am familiar with JSON, and I can see some readability benefits of using CSON. However, while I can find all sorts of parsers for CSON, I can’t find a detailed description of the syntax itself.
I understand that it uses indentation rather than braces, and is more forgiving in other respects.
I have checked the CoffeeScript site, Wikipedia (which has all of one paragraph on it), and a lot of web searches.
It’s simply the notation that CoffeeScript (an amazing language, BTW!) uses for declaring objects. You’ll find all necessary details on the CoffeeScript website!