WordPress at a glance
action is not described

untrash_post_comments action-hook . WP 2.9.0

Fires before comments are restored for a post from the trash.

Usage

add_action( 'untrash_post_comments', 'action_function_name_9840' );
function action_function_name_9840( $post_id ){
	// action...
}
$post_id(int)
Post ID.

Where the hook is called

wp_untrash_post_comments()
untrash_post_comments
wp-includes/post.php 2990
do_action( 'untrash_post_comments', $post_id );

Where the hook is used (in WP core)

Does not used.