This event is signalled by rss_buildItems() in feed.php when the cache isn't used and the feed mode is known, handlers can use it to modify the items that are added to the feed or process the data they've returned in FEED_MODE_UNKNOWN.
For compatibility the FEED_ITEM_ADD event should be called for each item instead of directly adding it to the feed creator object.
rss
: The feed creator objectdata
: The items to addopt
: The feed options