parent_post_rel_link │ filter-hook │ WP 1.0

Usage

add_filter( 'parent_post_rel_link', 'wp_kama_parent_post_rel_link_filter' );

/**
 * Function for `parent_post_rel_link` filter-hook.
 * 
 * @param  $link 
 *
 * @return 
 */
function wp_kama_parent_post_rel_link_filter( $link ){

	// filter...
	return $link;
}

$link

-

Where the hook is called

return apply_filters( "parent_post_rel_link", $link );

Where the hook is used in WordPress