diff --git a/epan/dissectors/packet-asap.c b/epan/dissectors/packet-asap.c
index f43c174649..dfd67f58ee 100644
--- a/epan/dissectors/packet-asap.c
+++ b/epan/dissectors/packet-asap.c
@@ -845,7 +845,7 @@ dissect_asap(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the asap protocol tree */
-    asap_item = proto_tree_add_item(tree, proto_asap, message_tvb, 0, -1, FALSE);
+    asap_item = proto_tree_add_item(tree, proto_asap, message_tvb, 0, -1, REP_NA);
     asap_tree = proto_item_add_subtree(asap_item, ett_asap);
   } else {
     asap_tree = NULL;
diff --git a/epan/dissectors/packet-dua.c b/epan/dissectors/packet-dua.c
index 405f20b236..00623b96b3 100644
--- a/epan/dissectors/packet-dua.c
+++ b/epan/dissectors/packet-dua.c
@@ -696,7 +696,7 @@ dissect_dua(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the m3ua protocol tree */
-    dua_item = proto_tree_add_item(tree, proto_dua, message_tvb, 0, -1, FALSE);
+    dua_item = proto_tree_add_item(tree, proto_dua, message_tvb, 0, -1, REP_NA);
     dua_tree = proto_item_add_subtree(dua_item, ett_dua);
   } else {
     dua_tree = NULL;
diff --git a/epan/dissectors/packet-enrp.c b/epan/dissectors/packet-enrp.c
index 9c0486bee7..aa346a740c 100644
--- a/epan/dissectors/packet-enrp.c
+++ b/epan/dissectors/packet-enrp.c
@@ -1003,7 +1003,7 @@ dissect_enrp(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the enrp protocol tree */
-    enrp_item = proto_tree_add_item(tree, proto_enrp, message_tvb, 0, -1, FALSE);
+    enrp_item = proto_tree_add_item(tree, proto_enrp, message_tvb, 0, -1, REP_NA);
     enrp_tree = proto_item_add_subtree(enrp_item, ett_enrp);
   } else {
     enrp_tree = NULL;
diff --git a/epan/dissectors/packet-iua.c b/epan/dissectors/packet-iua.c
index 270ffc957d..6d379a78b8 100644
--- a/epan/dissectors/packet-iua.c
+++ b/epan/dissectors/packet-iua.c
@@ -888,7 +888,7 @@ dissect_iua(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the m3ua protocol tree */
-    iua_item = proto_tree_add_item(tree, proto_iua, message_tvb, 0, -1, FALSE);
+    iua_item = proto_tree_add_item(tree, proto_iua, message_tvb, 0, -1, REP_NA);
     iua_tree = proto_item_add_subtree(iua_item, ett_iua);
   } else {
     iua_tree = NULL;
diff --git a/epan/dissectors/packet-m2pa.c b/epan/dissectors/packet-m2pa.c
index 9d1cbc83c6..6a557e882e 100644
--- a/epan/dissectors/packet-m2pa.c
+++ b/epan/dissectors/packet-m2pa.c
@@ -532,7 +532,7 @@ dissect_m2pa(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
     };
 
   if (tree) {
-    m2pa_item = proto_tree_add_item(tree, proto_m2pa, tvb, 0, -1, FALSE);
+    m2pa_item = proto_tree_add_item(tree, proto_m2pa, tvb, 0, -1, REP_NA);
     m2pa_tree = proto_item_add_subtree(m2pa_item, ett_m2pa);
   } else {
     m2pa_item = NULL;
diff --git a/epan/dissectors/packet-m2ua.c b/epan/dissectors/packet-m2ua.c
index 868987882a..5ddf3535af 100644
--- a/epan/dissectors/packet-m2ua.c
+++ b/epan/dissectors/packet-m2ua.c
@@ -1059,7 +1059,7 @@ dissect_m2ua(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the m2ua protocol tree */
-    m2ua_item = proto_tree_add_item(tree, proto_m2ua, message_tvb, 0, -1, FALSE);
+    m2ua_item = proto_tree_add_item(tree, proto_m2ua, message_tvb, 0, -1, REP_NA);
     m2ua_tree = proto_item_add_subtree(m2ua_item, ett_m2ua);
   } else {
     m2ua_tree = NULL;
diff --git a/epan/dissectors/packet-m3ua.c b/epan/dissectors/packet-m3ua.c
index 8a6cefde12..dd3eeb303d 100644
--- a/epan/dissectors/packet-m3ua.c
+++ b/epan/dissectors/packet-m3ua.c
@@ -1963,7 +1963,7 @@ dissect_m3ua(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the m3ua protocol tree */
-    m3ua_item = proto_tree_add_item(tree, proto_m3ua, message_tvb, 0, -1, FALSE);
+    m3ua_item = proto_tree_add_item(tree, proto_m3ua, message_tvb, 0, -1, REP_NA);
     m3ua_tree = proto_item_add_subtree(m3ua_item, ett_m3ua);
   } else {
     m3ua_tree = NULL;
diff --git a/epan/dissectors/packet-mq.c b/epan/dissectors/packet-mq.c
index 4c9a60880a..d567220896 100644
--- a/epan/dissectors/packet-mq.c
+++ b/epan/dissectors/packet-mq.c
@@ -1276,7 +1276,7 @@ dissect_mq_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 
 			if (tree)
 			{
-				ti = proto_tree_add_item(tree, proto_mq, tvb, offset, -1, FALSE);
+				ti = proto_tree_add_item(tree, proto_mq, tvb, offset, -1, REP_NA);
 				proto_item_append_text(ti, " (%s)", val_to_str(opcode, mq_opcode_vals, "Unknown (0x%02x)"));
 				if (bEBCDIC == TRUE) proto_item_append_text(ti, " (EBCDIC)");
 				mqroot_tree = proto_item_add_subtree(ti, ett_mq);
@@ -2300,7 +2300,7 @@ dissect_mq_pdu(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 			col_append_str(pinfo->cinfo, COL_INFO, " [Undesegmented]");
 			if (tree)
 			{
-				proto_tree_add_item(tree, proto_mq, tvb, offset, -1, FALSE);
+				proto_tree_add_item(tree, proto_mq, tvb, offset, -1, REP_NA);
 			}
 			call_dissector(data_handle, tvb_new_subset_remaining(tvb, offset), pinfo, tree);
 		}
@@ -2367,7 +2367,7 @@ reassemble_mq(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
 						if (tree)
 						{
 							proto_item* ti = NULL;
-							ti = proto_tree_add_item(tree, proto_mq, tvb, 0, -1, FALSE);
+							ti = proto_tree_add_item(tree, proto_mq, tvb, 0, -1, REP_NA);
 							proto_item_append_text(ti, " (%s) [Reassembled MQ]", val_to_str(opcode, mq_opcode_vals, "Unknown (0x%02x)"));
 						}
 						return;
diff --git a/epan/dissectors/packet-mtp2.c b/epan/dissectors/packet-mtp2.c
index 1ba82c669b..8b2edc6d9c 100644
--- a/epan/dissectors/packet-mtp2.c
+++ b/epan/dissectors/packet-mtp2.c
@@ -345,7 +345,7 @@ dissect_mtp2_common(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolea
   col_set_str(pinfo->cinfo, COL_PROTOCOL, "MTP2");
   
   if (tree) {
-    mtp2_item = proto_tree_add_item(tree, proto_mtp2, tvb, 0, -1, FALSE);
+    mtp2_item = proto_tree_add_item(tree, proto_mtp2, tvb, 0, -1, REP_NA);
     mtp2_tree = proto_item_add_subtree(mtp2_item, ett_mtp2);
   };
 
diff --git a/epan/dissectors/packet-sctp.c b/epan/dissectors/packet-sctp.c
index 361768a0fd..d8ef8c7522 100644
--- a/epan/dissectors/packet-sctp.c
+++ b/epan/dissectors/packet-sctp.c
@@ -3695,7 +3695,7 @@ dissect_sctp_chunks(tvbuff_t *tvb,
       offset += total_length;
       last_offset = offset;
       if (tvb_reported_length_remaining(tvb, offset) > 0) {
-        sctp_item = proto_tree_add_item(tree, proto_sctp, tvb, offset, -1, FALSE);
+        sctp_item = proto_tree_add_item(tree, proto_sctp, tvb, offset, -1, REP_NA);
         sctp_tree = proto_item_add_subtree(sctp_item, ett_sctp);
         sctp_item_length_set = FALSE;
       }
@@ -3774,7 +3774,7 @@ dissect_sctp_packet(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, gboolea
                                                  get_sctp_port(source_port), source_port,
                                                  get_sctp_port(destination_port), destination_port);
     else
-      sctp_item = proto_tree_add_item(tree, proto_sctp, tvb, 0, -1, FALSE);
+      sctp_item = proto_tree_add_item(tree, proto_sctp, tvb, 0, -1, REP_NA);
     sctp_tree = proto_item_add_subtree(sctp_item, ett_sctp);
 
     /* add the components of the common header to the protocol tree */
diff --git a/epan/dissectors/packet-sua.c b/epan/dissectors/packet-sua.c
index 4bc520add1..1ecb1ae8ad 100644
--- a/epan/dissectors/packet-sua.c
+++ b/epan/dissectors/packet-sua.c
@@ -1965,7 +1965,7 @@ dissect_sua(tvbuff_t *message_tvb, packet_info *pinfo, proto_tree *tree)
      necessary to generate protocol tree items. */
   if (tree) {
     /* create the sua protocol tree */
-    sua_item = proto_tree_add_item(tree, proto_sua, message_tvb, 0, -1, FALSE);
+    sua_item = proto_tree_add_item(tree, proto_sua, message_tvb, 0, -1, REP_NA);
     sua_tree = proto_item_add_subtree(sua_item, ett_sua);
   } else {
     sua_tree = NULL;
diff --git a/epan/proto.h b/epan/proto.h
index add3e28106..2266bf592a 100644
--- a/epan/proto.h
+++ b/epan/proto.h
@@ -187,10 +187,18 @@ typedef struct _protocol protocol_t;
  * REP_LITTLE_ENDIAN as 0x80000000 - we're using the high-order bit
  * so that we could put a field type and/or a value such as a character
  * encoding in the lower bits.
+ *
+ * For protocols (FT_PROTOCOL), aggregate items with subtrees (FT_NONE),
+ * opaque byte-array fields (FT_BYTES), and other fields where there
+ * is no choice of representation (either because it's "just a bucket
+ * of bytes" or because the representation is completely fixed), we
+ * have REP_NA (for "Not Applicable").
  */
 #define REP_BIG_ENDIAN		0x00000000
 #define REP_LITTLE_ENDIAN	0x80000000
 
+#define REP_NA			0x00000000
+
 /* Values for header_field_info.display */
 
 /* For integral types, the display format is a base_display_e value
diff --git a/plugins/giop/packet-coseventcomm.c b/plugins/giop/packet-coseventcomm.c
index 0d05481d34..700920ec27 100644
--- a/plugins/giop/packet-coseventcomm.c
+++ b/plugins/giop/packet-coseventcomm.c
@@ -613,7 +613,7 @@ static proto_tree *start_dissecting(tvbuff_t *tvb, packet_info *pinfo, proto_tre
      */
 
     if (ptree) {
-        ti = proto_tree_add_item(ptree, proto_coseventcomm, tvb, *offset, -1, FALSE);
+        ti = proto_tree_add_item(ptree, proto_coseventcomm, tvb, *offset, -1, REP_NA);
         tree = proto_item_add_subtree(ti, ett_coseventcomm);
     }
     return tree;
diff --git a/plugins/giop/packet-cosnaming.c b/plugins/giop/packet-cosnaming.c
index bcde397d83..f98bd53af5 100644
--- a/plugins/giop/packet-cosnaming.c
+++ b/plugins/giop/packet-cosnaming.c
@@ -1560,7 +1560,7 @@ static proto_tree *start_dissecting(tvbuff_t *tvb, packet_info *pinfo, proto_tre
      */
 
     if (ptree) {
-        ti = proto_tree_add_item(ptree, proto_cosnaming, tvb, *offset, -1, FALSE);
+        ti = proto_tree_add_item(ptree, proto_cosnaming, tvb, *offset, -1, REP_NA);
         tree = proto_item_add_subtree(ti, ett_cosnaming);
     }
     return tree;
diff --git a/plugins/giop/packet-parlay.c b/plugins/giop/packet-parlay.c
index 1746d7e8f2..95561d2538 100644
--- a/plugins/giop/packet-parlay.c
+++ b/plugins/giop/packet-parlay.c
@@ -101303,7 +101303,7 @@ static proto_tree *start_dissecting(tvbuff_t *tvb, packet_info *pinfo, proto_tre
      */
 
     if (ptree) {
-        ti = proto_tree_add_item(ptree, proto_parlay, tvb, *offset, -1, FALSE);
+        ti = proto_tree_add_item(ptree, proto_parlay, tvb, *offset, -1, REP_NA);
         tree = proto_item_add_subtree(ti, ett_parlay);
     }
     return tree;
diff --git a/plugins/giop/packet-tango.c b/plugins/giop/packet-tango.c
index bc047b0203..b3ba38d603 100644
--- a/plugins/giop/packet-tango.c
+++ b/plugins/giop/packet-tango.c
@@ -4239,7 +4239,7 @@ static proto_tree *start_dissecting(tvbuff_t *tvb, packet_info *pinfo, proto_tre
      */
 
     if (ptree) {
-        ti = proto_tree_add_item(ptree, proto_tango, tvb, *offset, -1, FALSE);
+        ti = proto_tree_add_item(ptree, proto_tango, tvb, *offset, -1, REP_NA);
         tree = proto_item_add_subtree(ti, ett_tango);
     }
     return tree;
diff --git a/tools/wireshark_gen.py b/tools/wireshark_gen.py
index 19dd25a06e..d2942e34e4 100755
--- a/tools/wireshark_gen.py
+++ b/tools/wireshark_gen.py
@@ -2145,7 +2145,7 @@ static proto_tree *start_dissecting(tvbuff_t *tvb, packet_info *pinfo, proto_tre
      */
 
     if (ptree) {
-        ti = proto_tree_add_item(ptree, proto_@dissname@, tvb, *offset, -1, FALSE);
+        ti = proto_tree_add_item(ptree, proto_@dissname@, tvb, *offset, -1, REP_NA);
         tree = proto_item_add_subtree(ti, ett_@dissname@);
     }
     return tree;