WordPress at a glance
function is not described

trackback_response() WP 0.71

Response to a trackback.

Responds with an error or success XML message.

No Hooks.

Return

Nothing (null).

Usage

trackback_response( $error, $error_message );
$error(mixed)
Whether there was an error. Accepts '0' or '1', true or false.
Default: '0'
$error_message(string)
Error message if an error occurred.
Default: ''

Code of trackback response: wp-trackback.php VER 5.0.3

<?php
function trackback_response($error = 0, $error_message = '') {
	header('Content-Type: text/xml; charset=' . get_option('blog_charset') );
	if ($error) {
		echo '<?xml version="1.0" encoding="utf-8"?'.">\n";
		echo "<response>\n";
		echo "<error>1</error>\n";
		echo "<message>$error_message</message>\n";
		echo "</response>";
		die();
	} else {
		echo '<?xml version="1.0" encoding="utf-8"?'.">\n";
		echo "<response>\n";
		echo "<error>0</error>\n";
		echo "</response>";
	}
}