WordPress at a glance
action is not described

pre_ping action-hook . WP 2.0.0

Fires just before pinging back links found in a post.

Usage

add_action( 'pre_ping', 'action_function_name_8563', 10, 3 );
function action_function_name_8563( $post_links, $pung, $post_ID ){
	// action...
}
$post_links(array)
An array of post links to be checked (passed by reference).
$pung(array)
Whether a link has already been pinged (passed by reference).
$post_ID(int)
The post ID.

Where the hook is called

pingback()
wp-includes/comment.php 2643
do_action_ref_array( 'pre_ping', array( &$post_links, &$pung, $post->ID ) );

Where the hook is used (in WP core)

Does not used.