--- md_types same as after typecheck
--- md_insts ditto
--- md_rules orphan rules only (local ones attached to binds)
--- md_binds with rules attached
+-- md_types Same as after typecheck
+-- md_insts Ditto
+-- md_rules Orphan rules only (local ones now attached to binds)
+-- md_binds With rules attached
+--
+-- After CoreTidy
+-- md_types Now contains Ids as well, replete with final IdInfo
+-- The Ids are only the ones that are visible from
+-- importing modules. Without -O that means only
+-- exported Ids, but with -O importing modules may
+-- see ids mentioned in unfoldings of exported Ids
+--
+-- md_insts Same DFunIds as before, but with final IdInfo,
+-- and the unique might have changed; remember that
+-- CoreTidy links up the uniques of old and new versions