int sd_rtnl_message_append_string(sd_rtnl_message *m, unsigned short type, const char *data);
int sd_rtnl_message_append_u8(sd_rtnl_message *m, unsigned short type, uint8_t data);
int sd_rtnl_message_append_u16(sd_rtnl_message *m, unsigned short type, uint16_t data);
int sd_rtnl_message_append_string(sd_rtnl_message *m, unsigned short type, const char *data);
int sd_rtnl_message_append_u8(sd_rtnl_message *m, unsigned short type, uint8_t data);
int sd_rtnl_message_append_u16(sd_rtnl_message *m, unsigned short type, uint16_t data);