[blml] claim

[Guthrie]

[nige1]
North      East       South      West
C:x        C:Q10      dummy      C: J
H:AT8      H:xx                  D: 9xx
Suppose this had been the ending. From East's point of view the
position may look the same. But, in this ending, when North leads a
club, East must crocodile coup CQ to take 2 tricks. CT takes only one
trick. Hence, IMO, on Koen's actual hand, either ruling is arguable.

[Herman de Wael]
I don't believe this one causes any troubles - and it says nothing
about the other one. You take the view that only the cards are 
important, but that is not  the case. We must also consider the mind 
of the player. In the player's mind, his Q and T are both high.
We should have a rule telling us which cards are normal in certain
situations. That rule must be the same in both lies of the cards.

There are two possible rules:
- when winning a trick, it is always done with the lowest of the
possible cards; or
- when winning a trick, player can play any of his winning cards.

Under both rules, playing the 10 is normal.
Therefore, in the second case, the Jack will always win the trick and
declarer gets some more.
But in the first case, the outcome depends on which rule we use in
determining normal play.

[nige1]
OK Herman. I agree with you. By the way, my example had (another) 
stupid typo, corrected below

North      East       South      West
C:x        C:Q10      dummy      C: J
H:AT8      H:xx                  H: 9xx