Zelandakh, on 2011-November-20, 04:54, said:
@fromageGB, on your given auction would you lose alot by using 4H as natural and 4S as RKCB for diamonds? Obviously clarity is good but I think you could easily tweak the wording of the meta-agreement to be more effective overall.
Well, if you did change the agreement so that a possibly ambiguous bid was natural, rather than kickback, and use a higher bid for ace asking, you lose the space that kickback gives. Without that space, we cannot show all aces and trump queen yet still stop at 5♦, and when your next bid is one level up to ask for specific kings, there is no room to show them precisely and stop at 6♦. So you would need some sort of condensed responses that would not cater for all circumstances, and, importantly, take more memory.
Of course, in my hypothetical sequence, you could not have 4♠ as ace asking in diamonds anyway, as this is kickback for my heart suit.
In practice, I have been playing it for years and not yet had any situation where I regret the metarule no 2 that "if it could be ace asking, then it is".