When a suit has been agreed (bid and raised, or raised by inference--such as a An unusual jump showing 0-1 in that suit and support for partner splinter raise or conventional raise), that suit is trump for Abbreviation for A system to ask for not only the 4 aces, but the trump king as well Roman Keycard Blackwood RKC. If there was no suit agreement, then 4NT is Abbreviation for A system to ask for not only the 4 aces, but the trump king as well Roman Keycard Blackwood RKC for the last naturally-bid suit. Here are all the details.

Responding to Abbreviation for A system to ask for not only the 4 aces, but the trump king as well Roman Keycard Blackwood RKC with a void: If the location of the void will be known (from the previous bidding), show it as follows: 5NT=2 Keycards and a void; 6-level = a void and the same # of keycards as the 5-level response (so 6=1 or 4). If partner won't know where the void is, just ignore it (answer on the 5-level your # of keycards).

King-asking: 5NT guarantees all the keycards and asks for # of kings using plain old A 4NT bid to ask for aces (or in Abbreviation for A system to ask for not only the 4 aces, but the trump king as well Roman Keycard Blackwood RKC, keycards) Blackwood (6=0 or 4, 6=1, etc.)

If they interfere after 4NT, use DOPI: Double = 0-3 and Pass = 1-4 and bidding the next step= 2 keycards.

Conventional ace-ask used after notrump Gerber is used only when the last bid was 1NT or 2NT (plain Conventional ace-ask used after notrump Gerber 0/4, 1, 2, 3).

Note: There are many fancy options here, including kickback and specific kings. These require many hours of partnership work, which goes against the grain of LC Standard (to be used quickly and effectively by new partners as a starting point).