The Dutch one goes something like this:
1. Any opening bid on the 2 level or higher, or any skip bid, must be accompanied by a warning, described here:
a) With bidding boxes, you need to lay down the stop card so as both opponents can see it. If the stop card is missing, you should place your bid upside down (?!) and then turn them right side up.
b) Without bidding boxes, you should verbally announce the bid by saying 'stop!'.
2. After any bid described by 1., the next player should wait about 10 seconds before making his or her call.
3. None of this applies to screens.
This seems slightly weird to me - what does 2. say? I can read it in two different ways: either that you need to wait 10 seconds after any jump bid/2+ level opening bid (i.e. described by the first line), or that you need to wait 10 seconds after any jump bid/2+ opening bid if RHO made a proper warning. Furthermore, what's up with bidding upside down and when are you supposed to turn over the bidding cards? And what's the point of the stop card if you are not going to remove it? I don't get it.
What happened in this case was that my LHO just said 'stop' and made his jump overcall and my partner passed almost instantly. The director was called and he ruled that regardless of the use of the stop card, you always must wait 10 seconds. I asked him what he's basing this on because according to me this is written nowhere. He showed me this rule and my Dutch wasn't good enough to decipher the regulation on the spot and just believed him (apparently, he believes rule #2 means that the description of #1 refers just to the jump bid/2+ level opening part and not the stop card - in this case why use the stop card at all? surely we all can see that it is a jump overcall no?). For people who do not trust my translation above, this is the original text: