WordPress at a glance
function is not described

get_parent_post_rel_link() WP 2.8.0

Deprecated in from version 3.3.0. It is no longer supported and can be removed in future releases. It is recommended to replace this function with the same one.

Get parent post relational link.

Hooks from the function
Return

String.

Usage

get_parent_post_rel_link( $title );
$title(string)
Link title format.
Default: '%title'

Changelog

Since 2.8.0 Introduced.
Deprecated 3.3.0

Code of get_parent_post_rel_link() WP 5.5.1

<?php
function get_parent_post_rel_link( $title = '%title' ) {
	_deprecated_function( __FUNCTION__, '3.3.0' );

	if ( ! empty( $GLOBALS['post'] ) && ! empty( $GLOBALS['post']->post_parent ) )
		$post = get_post($GLOBALS['post']->post_parent);

	if ( empty($post) )
		return;

	$date = mysql2date(get_option('date_format'), $post->post_date);

	$title = str_replace('%title', $post->post_title, $title);
	$title = str_replace('%date', $date, $title);
	$title = apply_filters('the_title', $title, $post->ID);

	$link = "<link rel='up' title='";
	$link .= esc_attr( $title );
	$link .= "' href='" . get_permalink($post) . "' />\n";

	return apply_filters( "parent_post_rel_link", $link );
}