PHP within XML?

I am trying to figure out if it is possible to have PHP work within an XML document. The application is tracking RSS subscribers IP addresses within the database. I have wrote functions so the PHP code required is below is minimal, after the XML declaration line. Prior to posting this question I tried to have the PHP at the very start, but that doesn’t work, the declaration line needs to be first. Right now the PHP is displayed as a comment. Thoughts anyone? Ron === <?xml version="1.0" encoding="utf-8"?> <?php #load RSS XML function require_once("rss_subscribers_xml.php"); $ip_address = _ip; rss_subscriber_update($ip_address); ?> RSS content starts here ................ === Ron The Verse of the Day “Encouragement from God’s Word” http://www.TheVerseOfTheDay.info