--- openflow-2013-10-25.h	2015-07-23 09:54:17.584479380 -0700
+++ openflow-2013-11-25.h	2015-07-23 09:54:17.588479380 -0700
@@ -599,7 +599,9 @@
 };
 OFP_ASSERT(sizeof(struct ofp_match) == 8);
 
-/* Components of a OXM TLV header. */
+/* Components of a OXM TLV header.
+ * Those macros are not valid for the experimenter class, macros for the
+ * experimenter class will depend on the experimenter header used. */
 #define OXM_HEADER__(CLASS, FIELD, HASMASK, LENGTH) \
     (((CLASS) << 16) | ((FIELD) << 9) | ((HASMASK) << 8) | (LENGTH))
 #define OXM_HEADER(CLASS, FIELD, LENGTH) \
@@ -1110,7 +1112,9 @@
  * Masking: Not maskable. */
 #define OXM_OF_PBB_UCA    OXM_HEADER  (0x8000, OFPXMT_OFB_PBB_UCA, 1)
 
-/* Header for OXM experimenter match fields. */
+/* Header for OXM experimenter match fields.
+ * The experimenter class should not use OXM_HEADER() macros for defining
+ * fields due to this extra header. */
 struct ofp_oxm_experimenter_header {
     uint32_t oxm_header;        /* oxm_class = OFPXMC_EXPERIMENTER */
     uint32_t experimenter;      /* Experimenter ID. */