north deals, south held:
♠ AKQJxxx
♥ Qxx
♦ xx
♣ -
The bidding (all by N/S)
1H=2D (game force)
3C=3H
4H= 4NT (1430 for ♥)
5H=6S
Only a diamond lead sets the contract.
South stated that the 2♦ bid was to discourage a diamond lead.
Benefits include:
Plus... it's free!