[bzbarsky]

Assuming you mean RFC 4627, you're quoting the restrictions on what character streams can be called "JSON". The "should" means that if your names are not unique you can still call it "JSON", but you should think twice about it.

The parsing behavior for JSON is not defined at all in RFC 4627, actually. Browsers (and Node, since it's using a browser js engine) use the parsing specification in ECMA-262 edition 5 section 15.12.2.

Note that ES5 section 15.12 in general is much stricter than RFC 4627, as it explicitly points out if you read it.