Well, at least I find it peculiar. You can tell me otherwise in the comments, as usual.
Rule 18 is divided in five rules numbered 18.1 trough 18.5 and some of them even further divided into parts by using letters (a), (b), (c) etc. It makes it a very complex rule. It was worse in the previous rulebook were obstructions were also part of rule 18. But it is still one rule, with me so far?
The rule starts with giving us the exceptions - when rule 18 NOT applies, of which 18.1(b) is one of them.
On a side note: Uli came up with the only logical place on the race course (so far) where rule
Mark 2 on a trapezoid course.
Only 18.1(b) but not 18.1(a) apply between a port boat coming form mark 3 and a starboard boat coming from mark 1.
But back to my original point.
Although we agree it is a complex rule and written extremely well for it's purpose, there is, in my opinion, a logic flaw. If rule 18 is switched off within rule 18 itself (by part 18.1) how can rule 18 tell us that it is switched off? It is no longer applicable. If it's not applicable it can't be used, and if it can't be used it can't tell us it is switched off!
I'm sure that the writers have considered this, but I can't help thinking: "this is a circular reference, like we sometimes get in excel"
What do you think?