+int sd_rtnl_message_append_string(sd_rtnl_message *m, unsigned short type, const char *data);
+int sd_rtnl_message_append_u16(sd_rtnl_message *m, unsigned short type, uint16_t data);
+int sd_rtnl_message_append_u32(sd_rtnl_message *m, unsigned short type, uint32_t data);
+int sd_rtnl_message_append_in_addr(sd_rtnl_message *m, unsigned short type, const struct in_addr *data);
+int sd_rtnl_message_append_in6_addr(sd_rtnl_message *m, unsigned short type, const struct in6_addr *data);
+int sd_rtnl_message_append_ether_addr(sd_rtnl_message *m, unsigned short type, const struct ether_addr *data);
+