WordPress at a glance
action is not described

rdf_header action-hook . WP 2.0.0

Fires at the end of the RDF feed header.

Usage

add_action( 'rdf_header', 'action_function_name_4974' );
function action_function_name_4974(){
	// action...
}

Where the hook is called

In file: /wp-includes/feed-rdf.php
rdf_header
wp-includes/feed-rdf.php 55
do_action( 'rdf_header' );

Where the hook is used (in WP core)

wp-includes/default-filters.php 308
add_action( $action, 'the_generator' );