/* Appending attributes. */
void *nl_msg_put_unspec_uninit(struct ofpbuf *, uint16_t type, size_t);
+void *nl_msg_put_unspec_zero(struct ofpbuf *, uint16_t type, size_t);
void nl_msg_put_unspec(struct ofpbuf *, uint16_t type, const void *, size_t);
void nl_msg_put_flag(struct ofpbuf *, uint16_t type);
void nl_msg_put_u8(struct ofpbuf *, uint16_t type, uint8_t value);