Bbradley62, on 2015-December-23, 08:11, said:
(4NT over 3♠ was undefined, in case that occurs to anyone, and it didn't occur to me to preview the meaning of a second double.)
Yes.
All of 4NT over opening bids at one level are undefined.
All of 4NT over opening bids at three level are undefined.
Let's listen to what Barmar said :
barmar, on 2015-July-23, 12:14, said:
Programming the rules for bidding is incredibly complicated. The part of GIB that implements its bidding rules is over 6,000 lines in an incredibly compact language (not including over 2500 lines of comments explaining what's going on in the code lines).