This event is signalled by rss_BuildItems() in feed.php when the feed is build. You can use this to manipulate feed items before they are added to the feed. Eg. you could add advertising banners or add additional links in the description.

• $data['item'] - The Feed Item object prepared for insertion in the feed
• $data['opt'] - associative array of feed options
• $data['ditem'] - the raw item data as it was given to the rss_BuildItems function
• $data['rss'] - the full feed creator object

The following plugins are known to handle this event and their source code may be a good start for understanding and implementing a handler yourself.

• feedmod

• Code related to this event
• Action Plugins
• Events
• Syndication