after_wpcfe_save_shipment – saving hook in WPCargo Frontend Manager add-ons.

save_post_wpcargo_shipment – saving hook in WPCargo plugin.

Frontend Manager Sample code

add_action( 'after_wpcfe_save_shipment', 'custom_after_wpcfe_save_shipment', 10, 2 );
function custom_after_wpcfe_save_shipment( $post_id, $post ){
    if( isset( $post['custom-field'] ) ){
        update_post_meta( $post_id, 'custom-field', $post['custom-field'] );
    }
}

WPCargo FREE Sample code

add_action( 'save_post_wpcargo_shipment', 'custom_save_post_wpcargo_shipment', 10, 2 );
function custom_save_post_wpcargo_shipment( $post_id, $post ){
    if( isset( $post['custom-field'] ) ){
        update_post_meta( $post_id, 'custom-field', $post['custom-field'] );
    }
}