<HTML>I have run into another strange interaction between a macro and module, where my macro behaves differently when defined outside a module versus inside a module: As an example, I give the following small module and macro definition: (module ex mzscheme   (provide test)     (define-syntax (test stx)     (syntax-case stx (-)       ((_ (- a b))        (syntax '(subtract a b)))       ((_ (op a b))        (syntax '(op a b)))))   ) When I test this macro (at the top level), (test (+ 3 4))   ==> (+ 3 4)   ;; this is "correct" and (test (- 3 4))    ==> (- 3 4)    ;; this is wrong! This is a silly macro, but the example with "-" yields the wrong result! But when I define this macro at the top-level, outside of a module, I get the correct result: (test (- 3 4))    ==> (subtract 3 4) Other symptoms: - if I change the "-" in this macro to "diff", (test (diff 3 4)) ==> (subtract 3 4)   (other names bound in to values, such as * and + also fail to work in this example) - names (presumably) bound to syntax, such as "or" work fine Jim </HTML>