function process_button() {
    global $order;
    $_SESSION['paypal_ec_markflow'] = 1;
    $process_button_string = '';
    $process_button_string .= "\n" . zen_draw_hidden_field('wpp_cc_type', $_POST['paypalwpp_cc_type']) . "\n" .
        zen_draw_hidden_field('wpp_cc_expdate_month', $_POST['paypalwpp_cc_expires_month']) . "\n" .
        zen_draw_hidden_field('wpp_cc_expdate_year', $_POST['paypalwpp_cc_expires_year']) . "\n" .
        zen_draw_hidden_field('wpp_cc_issuedate_month', $_POST['paypalwpp_cc_issue_month']) . "\n" .
        zen_draw_hidden_field('wpp_cc_issuedate_year', $_POST['paypalwpp_cc_issue_year']) . "\n" .
        zen_draw_hidden_field('wpp_cc_issuenumber', $_POST['paypalwpp_cc_issuenumber']) . "\n" .
        zen_draw_hidden_field('wpp_cc_number', $_POST['paypalwpp_cc_number']) . "\n" .
        zen_draw_hidden_field('wpp_cc_checkcode', $_POST['paypalwpp_cc_checkcode']) . "\n" .
        zen_draw_hidden_field('wpp_payer_firstname', $_POST['paypalwpp_cc_firstname']) . "\n" .
        zen_draw_hidden_field('wpp_payer_lastname', $_POST['paypalwpp_cc_lastname']) . "\n";
    $process_button_string .= zen_draw_hidden_field(zen_session_name(), zen_session_id());
    return $process_button_string;
  }