note 11600 added to setcookie

There's something about the domain part of Netscape's cookie specification that I can't agree with: How can it be mandatory to specify a domain with three periods if it's not one of the seven special toplevel domains? What domain would I specify if I wanted a global cookie to yahoo.dk? I could use www.yahoo.dk, but that would leave out sites like mail.yahoo.dk, and there's still only two period in the domain. Is there something wrong with Netscape's specifications, or am I reading the specs wrong? (And how does PHP handle the problem?) http://dk.php.net/manual/en/function.setcookie.php