Is there a way to configure my project tasks to prevent them from being available in purchasing

Hi!

I am wondering if there is a configuration / task option setting to limit the list of tasks in the Purchasing side, specifically when creating a Purchase Order.

There are tasks on my financial project that are labor-only tasks which buyers should not be able to select. Is there a way to classify the task on the Financial Project Plan that would prevent them from appearing available on the PO?