note 21637 added to language.variables.predefined

I am trying to find a simple code for printer friendly pages. The one I found doesn't seem to work. Any help will be apreciated. Here is the code. $fd= fread(fopen($HTTP_REFERER, "r"), 100000); if ($fd) { $start= strpos($fd, "<!-- CONTENT -->"); $finish= strpos($fd, "<!-- /CONTENT -->"); $length= $finish-$start; $code=Substr($fd, $start, $length); } The error I get says: Warning: fopen("", "r") - Inappropriate ioctl for device in "/home/blah/blah" Warning: Supplied argument is not a valid File-Handle resource in "/home/blah/blah" -- http://www.php.net/manual/en/language.variables.predefined.php http://master.php.net/manage/user-notes.php?action=edit+21637 http://master.php.net/manage/user-notes.php?action=delete+21637 http://master.php.net/manage/user-notes.php?action=reject+21637