UAX 29 questions

[Karl Williamson]

I vaguely recall asking something like this before, but if so, I didn't 
save the answers, and a search of the archives didn't turn up anything.

Some of the rules in UAX #29 don't make sense to me.

For example, rule WB7a
   Hebrew_Letter 	× 	Single_Quote

seems to say that a Hebrew_Letter followed by a Single Quote shouldn't 
break.  (And Rule WB4 says that actually there can be Extend and Format 
characters between the two and those should be ignored).

But the earlier rule, WB6

  (ALetter | Hebrew_Letter) 	× 	(MidLetter | MidNumLet | Single_Quote) 
(ALetter | Hebrew_Letter)

seems to me to say (among other things) that a Hebrew Letter followed by 
a Single Quote shouldn't break if and only if the latter is also 
followed by either an ALetter or another Hebrew Letter (again modulo 
ignored Format and Extend letters)

This seems contradictory.  One rule says something unconditionally, and 
the other rule adds conditions.