/* Body of extended data message. May be sent by either the switch or the
* controller to send messages that are greater than 65535 bytes in
- * length.
+ * length. The OpenFlow transaction id (xid) must be the same for all
+ * the individual OpenFlow messages that make up an extended message.
*
* OFMPT_EXTENDED_DATA (switch <-> controller) */
struct ofmp_extended_data {