+/* HAS_MSG_CTRUNC:
+ * This symbol, if defined, indicates that the MSG_CTRUNC is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_MSG_DONTROUTE:
+ * This symbol, if defined, indicates that the MSG_DONTROUTE is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_MSG_OOB:
+ * This symbol, if defined, indicates that the MSG_OOB is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_MSG_PEEK:
+ * This symbol, if defined, indicates that the MSG_PEEK is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_MSG_PROXY:
+ * This symbol, if defined, indicates that the MSG_PROXY is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_SCM_RIGHTS:
+ * This symbol, if defined, indicates that the SCM_RIGHTS is supported.
+ * Checking just with #ifdef might not be enough because this symbol
+ * has been known to be an enum.
+ */
+/* HAS_SENDMSG:
+ * This symbol, if defined, indicates that the sendmsg is supported
+ * to send messages between sockets. You will also need struct
+ * iovec from <sys/uio.h>, HAS_STRUCT_IOVEC and I_SYSUIO.
+ */
+/* HAS_RECVMSG:
+ * This symbol, if defined, indicates that the recvmsg is supported
+ * to send messages between sockets. You will also need struct
+ * iovec from <sys/uio.h>, HAS_STRUCT_IOVEC and I_SYSUIO.
+ */
+/* HAS_STRUCT_MSGHDR:
+ * This symbol, if defined, indicates that the struct msghdr
+ * (BSD 4.3 or 4.4) is supported. You will also need struct
+ * iovec from <sys/uio.h>, HAS_STRUCT_IOVEC and I_SYSUIO.
+ */
+/* HAS_STRUCT_CMSGHDR:
+ * This symbol, if defined, indicates that the struct cmsghdr
+ * (BSD 4.4) is supported. You will also need struct
+ * iovec from <sys/uio.h>, HAS_STRUCT_IOVEC and I_SYSUIO.
+ */
+#$d_socket HAS_SOCKET /**/
+#$d_sockpair HAS_SOCKETPAIR /**/
+#$d_msg_ctrunc HAS_MSG_CTRUNC /**/
+#$d_msg_dontroute HAS_MSG_DONTROUTE /**/
+#$d_msg_oob HAS_MSG_OOB /**/
+#$d_msg_peek HAS_MSG_PEEK /**/
+#$d_msg_proxy HAS_MSG_PROXY /**/
+#$d_scm_rights HAS_SCM_RIGHTS /**/
+#$d_sendmsg HAS_SENDMSG /**/
+#$d_recvmsg HAS_RECVMSG /**/
+#$d_msghdr_s HAS_STRUCT_MSGHDR /**/
+#$d_cmsghdr_s HAS_STRUCT_CMSGHDR /**/