Hello Panu,

 > Rewrite-based identifier systems are often vulnerable to situations
 > where the same definition is used multiple times in the same rewriting
 > context.  For example, if one has a macro that gets another macro as
 > input (is this possible in the system?) and contains some free variable,
 > and you give it as input to itself, is the outer instance of the macro
 > able to capture the free variable of the inner instance of the macro?

 If I understand correctly, the answer no, hygiene will prevent that from
 happening.  But if you are able to sketch an example (even if not fully
 fleshed out, or in pseudocode), I would be able to give you a more precise
 answer.

 Cheers
 Andre