I wrote:
> We do have the binding-strength question addressed explicitly somewhere
> else, I believe (probably on the SELECT reference page). I don't really
> feel a need to duplicate that here. I think the footnote approach might
> be the best solution.
I experimented with that and ended up not liking the <footnote> solution,
mainly because this text is near the top of a very long <sect1>, so that
the footnote is very very far away from where it's referenced (at least
in HTML rendering). I ended up just making it a regular <note> and then
rearranging some of the existing text so that we weren't
forward-referencing the concept of nested JOIN clauses. I think this is
a good answer: although we do have the syntactic explanation on the SELECT
reference page, it's not bad to have it here too as long as we can work it
into subsidiary material.
http://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=8372304e3594a1d67737df779f098d9ae9937603
regards, tom lane