+#define DARWIN_API_AVAILABLE_20180727 \
+ API_AVAILABLE(macos(10.15), ios(13.0), tvos(13.0), watchos(6.0))
+#define DARWIN_API_AVAILABLE_20181020 \
+ API_AVAILABLE(macos(10.15), ios(13.0), tvos(13.0), watchos(6.0))
+#define DARWIN_API_AVAILABLE_20181020 \
+ API_AVAILABLE(macos(10.15), ios(13.0), tvos(13.0), watchos(6.0))
+#define DARWIN_API_AVAILABLE_20190830 \
+ API_AVAILABLE(macos(10.15.2), ios(13.3), tvos(13.3), watchos(6.1.1))
+#define DARWIN_API_AVAILABLE_20191015 \
+ API_AVAILABLE(macos(10.15.2), ios(13.3), tvos(13.3), watchos(6.1.1))
+#define DARWIN_API_AVAILABLE_20200220 \
+ API_AVAILABLE(macos(10.16), ios(14.0), tvos(14.0), watchos(7.0))
+#define DARWIN_API_AVAILABLE_20200401 \
+ API_AVAILABLE(macos(10.16), ios(14.0), tvos(14.0), watchos(7.0))
+#define DARWIN_API_AVAILABLE_20200526 \
+ API_AVAILABLE(macos(10.16), ios(14.0), tvos(14.0), watchos(7.0))
+#else
+#define DARWIN_API_AVAILABLE_20170407
+#define DARWIN_API_AVAILABLE_20180727
+#define DARWIN_API_AVAILABLE_20181020
+#define DARWIN_API_AVAILABLE_20190830
+#define DARWIN_API_AVAILABLE_20191015
+#define DARWIN_API_AVAILABLE_20200220
+#define DARWIN_API_AVAILABLE_20200401
+#define DARWIN_API_AVAILABLE_20200526
+#endif
+
+/*!
+ * @typedef os_struct_magic_t
+ * A type representing the magic number of a transparent structure.
+ */
+typedef uint32_t os_struct_magic_t;
+
+/*!
+ * @typedef os_struct_version_t
+ * A type representing the version of a transparent structure.
+ */
+typedef uint32_t os_struct_version_t;