WordPress at a glance
function is not described

_ajax_wp_die_handler() WP 3.4.0

Kill WordPress ajax execution.

This is the handler for wp_die when processing Ajax requests.

No Hooks.

Return

Nothing (null).

Usage

_ajax_wp_die_handler( $message, $title, $args );
$message(string) (required)
Error message.
$title(string)
Error title (unused).
Default: ''
$args(string/array)
Arguments to control behavior.
Default: empty array

Code of ajax wp die handler: wp-includes/functions.php VER 5.0.3

<?php
function _ajax_wp_die_handler( $message, $title = '', $args = array() ) {
	$defaults = array(
		'response' => 200,
	);
	$r = wp_parse_args( $args, $defaults );

	if ( ! headers_sent() && null !== $r['response'] ) {
		status_header( $r['response'] );
	}

	if ( is_scalar( $message ) )
		die( (string) $message );
	die( '0' );
}