>From reading the camlp5 documentation, I've managed to write a syntax
extension that adds a new expression starting with a distinct keyword,
and it seems to work fine.  However, if I want to experiment with
infix notations, things get a little trickier.  I need to specify it's
precedence and associativity, of course.

So, there is a list of syntactic structures on this page:
http://pauillac.inria.fr/~ddr/camlp5/doc/htmlc/ast_transi.html

1) Where can I find the "level names" for each of these syntactic
constructs, for use with BEFORE, LIKE, etc?  Is that what the
"Comment" column is for?

2) I am confused by the fact that this is a list is for the revised
syntax.  I think most people (including me) want to modify the
original syntax.  e.g., imagine that I want to modify the record
update operator "<-" in the original syntax---I need to refer to it
somehow, but it doesn't even appear in the list.

 - Aaron