Flat rate shipping based on master category ID?

[snowgoose]

You can use the code in RED and adapt it as needed:

      // disable only when entire cart is free shipping
      if (zen_get_shipping_enabled($this->code)) {
        $this->enabled = ((MODULE_SHIPPING_FLAT_STATUS == 'True') ? true : false);
      }

// bof: only show for category 1, 4 and 5
      $chk_cat = 0;
      $chk_cat += $_SESSION['cart']->in_cart_check('master_categories_id','1');
      $chk_cat += $_SESSION['cart']->in_cart_check('master_categories_id','4');
      $chk_cat += $_SESSION['cart']->in_cart_check('master_categories_id','5');
      if ($chk_cat != $_SESSION['cart']->show_total()) {
        $this->enabled = false;
      }
// eof: only show for category 1, 4 and 5

Thanks very much for that :)