+ * should not be used in the wrong hands. The passed in 'list' contains
+ * several header fields at the beginning that are not part of the
+ * inversion list body proper */
+
+ const STRLEN length = (STRLEN) list[0];
+ const UV version_id = list[1];
+ const bool offset = cBOOL(list[2]);
+#define HEADER_LENGTH 3
+ /* If any of the above changes in any way, you must change HEADER_LENGTH
+ * (if appropriate) and regenerate INVLIST_VERSION_ID by running
+ * perl -E 'say int(rand 2**31-1)'
+ */
+#define INVLIST_VERSION_ID 148565664 /* This is a combination of a version and
+ data structure type, so that one being
+ passed in can be validated to be an
+ inversion list of the correct vintage.
+ */