PhilKing, on 2013-April-20, 10:53, said:
This convention neatly solves that age-old question - what to to with a 1-0-7-5 when partner opens our five-card suit and righty finds the Pass card.

You got me there! My example hand (cleverly crafted for clarity and simplicity to illustrate the point) never comes up, so my Silver convention is useless, and it is much better to use a jump to 4NT the way you and your partner have defined it.

You do have a clearly defined better meaning for a jump to 4NT that you will share with us along with a few example hands, don't you?
Now that we know there is never a time when you might care if there are trump losers, humor me as I ask about other situations that also cannot ever happen. Suppose your partner opens a weak two in a suit you hold three small, along with enough aces, kings, and other stuff to consider bidding six or seven. The opponents can cooperate by your RHO bidding anything from pass up through 3S. Now you have the simple task of deciding how many trump losers you have so you will then know how high to bid. How do you do that? Or maybe your partner bids a weak jump overcall, or opens a three level preempt in your small doubleton, and your RHO bids anything from pass up through 3S. How do you know how many trump losers to expect?
Sorry for pressing the point, because none of those situations could ever happen either. Here is one that can happen, and did with me a few days ago. Partner held Void, AKQT9 Txx KQxxx. He opened 1H, I bid 2C, he raised to 3C (setting up a slam try sequence), and I bid 3D. The opponents found their pass cards with no difficulty. Assuming that my 3D showed the DA, partner needed to know only whether or not I also held the CA. If he could have bid 4S as exclusion Blackwood, that would have solved this problem, but we had not discussed that possibility, so partner had to guess how high to bid. Since 4D would have been Kickback and we have no clearly defined alternative meaning for a jump to 4NT, using that jump as Silver to ask for trump honors would have worked well for us.