Doing a search on developer.netscape.com Give me this page:
http://developer.netscape.com:80/docs/manuals/js/client/jsref/document.htm
Which states the same thing. Doing a search on Google gives me this:
http://portal.research.bell-labs.com/~dmk/cookie.html They mention RFC 2965. I am going through it to see what I can find out.. looks like they suggest it be URL encoded.