+ - simplify metagrammar => go to top-down rewriting => finalize metagrammar and rdp-op's
+
+ - What is our use model?
+ - Parse, attribute, unify (ag)
+ - Parse, transform tree, walk (rdp)
+ - Parse, walk
+ - cascading tree rewrites
+
+ ==> use the middle formalism "for now" and in meta.g; layer others
+ on top of it
+