WordPress at a glance
action is not described

xmlrpc_rsd_apis action-hook . WP 3.5.0

Add additional APIs to the Really Simple Discovery (RSD) endpoint.

Usage

add_action( 'xmlrpc_rsd_apis', 'action_function_name_412' );
function action_function_name_412(){
	// action...
}

Where the hook is called

In file: /xmlrpc.php
xmlrpc_rsd_apis
xmlrpc.php 53
do_action( 'xmlrpc_rsd_apis' );

Where the hook is used (in WP core)

wp-includes/default-filters.php 257
add_action( 'xmlrpc_rsd_apis', 'rest_output_rsd' );