WordPress at a glance
function is not described

the_date_xml() WP 1.0.0

Outputs the date in iso8601 format for xml files.

No Hooks.

Return

Nothing (null).

Usage

the_date_xml();

Code of the date xml: wp-includes/general-template.php VER 5.0.3

<?php
function the_date_xml() {
	echo mysql2date( 'Y-m-d', get_post()->post_date, false );
}