Andre van Tonder <xxxxxx@now.het.brown.edu> writes:

> For each identifier, the expander needs to keep track of its binding
> at all different levels of the syntactic tower.

I would say: for each level of the syntactic tower, the expander needs
to keep track of bindings of all identifiers there.

--
   __("<         Marcin Kowalczyk
   \__/       xxxxxx@knm.org.pl
    ^^     http://qrnik.knm.org.pl/~qrczak/