WordPress at a glance
filter is not described

default_feed filter-hook . WP 2.5.0

Filters the default feed type.

Usage

add_filter( 'default_feed', 'filter_function_name_8397' );
function filter_function_name_8397( $feed_type ){
	// filter...

	return $feed_type;
}
$feed_type(string)
Type of default feed. Possible values include 'rss2', 'atom'.
Default: 'rss2'

Where the hook is called

get_default_feed()
default_feed
wp-includes/feed.php 87
$default_feed = apply_filters( 'default_feed', 'rss2' );

Where the hook is used (in WP core)

Does not used.