wp_shortlink_header() │ WP 3.0.0

Sends a Link: rel=shortlink header if a shortlink is defined for the current page.

Attached to the wp action.

Uses: wp_get_shortlink()

No Hooks.

Return

null. Nothing.

Usage

wp_shortlink_header();

Changelog

Since 3.0.0 Introduced.

Code of wp_shortlink_header() WP 5.9.3

wp-includes/link-template.php 
function wp_shortlink_header() {
	if ( headers_sent() ) {
		return;
	}

	$shortlink = wp_get_shortlink( 0, 'query' );

	if ( empty( $shortlink ) ) {
		return;
	}

	header( 'Link: <' . $shortlink . '>; rel=shortlink', false );
}

PHP headers (cookies)