+/* Action structure for NXAST_NOTE.
+ *
+ * This action has no effect. It is variable length. The switch does not
+ * attempt to interpret the user-defined 'note' data in any way. A controller
+ * can use this action to attach arbitrary metadata to a flow.
+ *
+ * This action might go away in the future.
+ */
+struct nx_action_note {
+ uint16_t type; /* OFPAT_VENDOR. */
+ uint16_t len; /* A multiple of 8, but at least 16. */
+ uint32_t vendor; /* NX_VENDOR_ID. */
+ uint16_t subtype; /* NXAST_NOTE. */
+ uint8_t note[6]; /* Start of user-defined data. */
+ /* Possibly followed by additional user-defined data. */
+};
+OFP_ASSERT(sizeof(struct nx_action_note) == 16);
+