ASL/Supplier warning functionality

Is there a functionality that I can use to create a warning in the purchase order  form when certain suppliers are selected.  Similar to the 'on hold' flag available at supplier header, however, this should be a soft warning that prompts the buyer to check if there are any outstanding issues with the supplier but allows them to approve the purchase order.

I wondered if this might be achieved in ASL, however suppliers are not currently restricted by item or commodity type.

Any feedback or thoughts would be appreciated.