trackback example

$excerpt = str_replace( ']]>', ']]>', $excerpt );
    $excerpt = wp_html_excerpt( $excerpt, 252, '…' );

    /** This filter is documented in wp-includes/post-template.php */
    $post_title = apply_filters( 'the_title', $post->post_title, $post->ID );
    $post_title = strip_tags( $post_title );

    if ( $to_ping ) {
        foreach ( (array) $to_ping as $tb_ping ) {
            $tb_ping = trim( $tb_ping );
            if ( ! in_array( $tb_ping, $pinged, true ) ) {
                trackback( $tb_ping, $post_title, $excerpt, $post->ID );
                $pinged[] = $tb_ping;
            } else {
                $wpdb->query(
                    $wpdb->prepare(
                        "UPDATE $wpdb->posts SET to_ping = TRIM(REPLACE(to_ping, %s, '')) WHERE ID = %d",
                        $tb_ping,
                        $post->ID
                    )
                );
            }
        }

// Form an excerpt.         $excerpt = strip_tags( $postdata['post_excerpt'] ? $postdata['post_excerpt'] : $postdata['post_content'] );

        if ( strlen( $excerpt ) > 255 ) {
            $excerpt = substr( $excerpt, 0, 252 ) . '…';
        }

        $trackback_urls = explode( ',', $tb_list );
        foreach ( (array) $trackback_urls as $tb_url ) {
            $tb_url = trim( $tb_url );
            trackback( $tb_url, wp_unslash( $postdata['post_title'] ), $excerpt, $post_id );
        }
    }
}

// // Page functions. //
/** * Gets a list of page IDs. * * @since 2.0.0 * * @global wpdb $wpdb WordPress database abstraction object. * * @return string[] List of page IDs as strings. */