WordPress at a glance
function is not described

html_type_rss() WP 2.2.0

Display the HTML type based on the blog setting.

The two possible values are either 'xhtml' or 'html'.

No Hooks.

Return

Nothing (null).

Usage

html_type_rss();

Code of html type rss: wp-includes/feed.php VER 5.1.1

<?php
function html_type_rss() {
	$type = get_bloginfo( 'html_type' );
	if ( strpos( $type, 'xhtml' ) !== false ) {
		$type = 'xhtml';
	} else {
		$type = 'html';
	}
	echo $type;
}