+/* Register of known Method Resolution Orders.
+ What this actually points to is an implementation detail (it may change to
+ a structure incorporating a reference count - use mro_get_from_name to
+ retrieve a C<struct mro_alg *> */
+PERLVAR(Iregistered_mros, HV *)
+
+/* Compile-time block start/end hooks */
+PERLVAR(Iblockhooks, AV *)
+
+/* Everything that folds to a given character, for case insensitivity regex
+ * matching */
+PERLVARI(Iutf8_foldclosures, HV *, NULL)
+
+/* List of characters that participate in folds (except marks, etc in
+ * multi-char folds) */
+PERLVARI(Iutf8_foldable, SV *, NULL)
+
+PERLVAR(Icustom_ops, HV *) /* custom op registrations */
+
+PERLVAR(Ireentrant_retint, int) /* Integer return value from reentrant functions */
+