How to see what is captured in $_COOKIE Superglobal

How do I create a script that shows me what data is captured in the $_COOKIE superglobal. The php docs describe the $_COOKIE superglobal, but don't enumerate the contents of the array (the docs do a great job of enumerating what is captured in the $_SERVER array). I am setting cookies and I can, obviously, open one of the files stored but it contains more than the value of the cookie and cookie name. I just don't know what its significance is. TIA Mike