~Grand Slam Force (TRY)

Grand Slam Force: A better term for this bid would be “Grand Slam Try.” A jump to 5NT after a major suit is agreed asks partner to bid seven of the agreed suit if holding two of the top three trump honors.  The following responses allow the asking partner to determine specific information that may still allow the partnership to make the best bid at the six level or to take a calculated risk of bidding seven even when missing one of the top honors:
~6C shows the ace or king (but not both) of the top two honors. 
~6D shows the queen of trumps only of the top three honors. 
~Six of the trump suit denies the ability to make any other response.
~Seven of the trump suit shows two of the top three trump honors.

After responder’s bid, partner may be able to correct to 6NT or 7NT for a top score.