+/* Access function */
+int gras_datadesc_size(gras_datadesc_type_t type);
+/* Described data exchanges: direct use */
+int gras_datadesc_copy(gras_datadesc_type_t type, void *src, void *dst);
+void gras_datadesc_send(gras_socket_t sock, gras_datadesc_type_t type, void *src);
+void gras_datadesc_recv(gras_socket_t sock, gras_datadesc_type_t type,
+ int r_arch, void *dst);