David, You have probably fixed this by now, but on multi-parameter predicates, the `extra' values are not pop'ed off the stack. E.g.: "(< 2 1 3)" bombs because the interpreter sees `3', rather than a continuation [the fix is trivial]. Thanks for XScheme. I have done a simple port to the Amiga and have hacked some graphics primitives. Much fun! -Ken Dickey kend@mrloog.WR.TEK.COM