1 files changed, 40 insertions, 36 deletions

diff --git a/draft-schanzen-r5n.xml b/draft-schanzen-r5n.xml
index 037adc5..60c5967 100644
--- a/draft-schanzen-r5n.xml
+++ b/draft-schanzen-r5n.xml
@@ -893,7 +893,34 @@ BEGIN
           This section describes some data structures and fields shared
           by various message types.
         </t>
-        <section anchor="route_flags">
+        <section anchor="msg_hdr">
+          <name>Header</name>
+          <t>
+            A message header that identifies the message length and type is shared across
+            all messages used in the R<sup>5</sup>N protocol.
+          </t>
+          <figure anchor="figure_msghdr" title="The common message header.">
+            <artwork name="" type="" align="left" alt=""><![CDATA[
+0     8     16    24
++-----+-----+-----+-----+
+|  MSIZE    |   MTYPE   |
++-----+-----+-----+-----+
+]]></artwork>
+          </figure>
+          <t>where:</t>
+          <dl>
+            <dt>MSIZE</dt>
+            <dd>
+              denotes the size of this message in network byte order.
+            </dd>
+            <dt>MTYPE</dt>
+            <dd>
+              is the 16-bit message type. Message types are registered in
+              the GANA "GNUnet Message Type" registry <xref target="gana_message_type"/>.
+            </dd>
+          </dl>
+        </section>
+        <section anchor="route_flags">
           <name>Flags</name>
           <t>
             Flags is a 16-bit vector representing binary options.
@@ -1217,7 +1244,7 @@ BEGIN
             <artwork name="" type="" align="left" alt=""><![CDATA[
 0     8     16    24    32    40    48    56
 +-----+-----+-----+-----+-----+-----+-----+-----+
-|  MSIZE    |   MTYPE   | RESERVED  | URL_CTR   |
+|        HEADER         | RESERVED  | URL_CTR   |
 +-----+-----+-----+-----+-----+-----+-----+-----+
 |                    SIGNATURE                  /
 /                   (64 byte)                   |
@@ -1230,13 +1257,9 @@ BEGIN
           </figure>
           <t>where:</t>
           <dl>
-            <dt>MSIZE</dt>
-            <dd>
-              denotes the size of this message in network byte order.
-            </dd>
-            <dt>MTYPE</dt>
+            <dt>HEADER</dt>
             <dd>
-              is the 16-bit message type. It must be set to
+              the common message header. Its <tt>MTYPE</tt> field must be set to
               the value 157 in network byte order.
             </dd>
             <dt>RESERVED</dt>
@@ -1325,7 +1348,7 @@ BEGIN
             <artwork name="" type="" align="left" alt=""><![CDATA[
 0     8     16    24    32    40    48    56
 +-----+-----+-----+-----+-----+-----+-----+-----+
-|  MSIZE    |   MTYPE   |         BTYPE         |
+|        HEADER         |         BTYPE         |
 +-----+-----+-----+-----+-----+-----+-----+-----+
 |   FLAGS   | HOPCOUNT  | REPL_LVL  | PATH_LEN  |
 +-----+-----+-----+-----+-----+-----+-----+-----+
@@ -1349,15 +1372,9 @@ BEGIN
           </figure>
           <t>where:</t>
           <dl>
-            <dt>MSIZE</dt>
-            <dd>
-              denotes the size of this message in network byte order.
-              Set by the initiator.
-              Modified by processing peers when message contents such as the path lengths change.
-            </dd>
-            <dt>MTYPE</dt>
+            <dt>HEADER</dt>
             <dd>
-              is the 16-bit message type. It is set by the initiator to
+              is the common message header. Its <tt>MTYPE</tt> field is set by the initiator to
               the value 146 in network byte order. Read-only.
             </dd>
             <dt>BTYPE</dt>
@@ -1571,7 +1588,7 @@ BEGIN
             <artwork name="" type="" align="left" alt=""><![CDATA[
 0     8     16    24    32    40    48    56
 +-----+-----+-----+-----+-----+-----+-----+-----+
-|  MSIZE    |   MTYPE   |         BTYPE         |
+|        HEADER         |         BTYPE         |
 +-----+-----+-----+-----+-----+-----+-----+-----+
 |   FLAGS   |  HOPCOUNT | REPL_LVL  |  RF_SIZE  |
 +-----+-----+-----+-----+-----+-----+-----+-----+
@@ -1590,16 +1607,9 @@ BEGIN
           </figure>
           <t>where:</t>
           <dl>
-            <dt>MSIZE</dt>
+            <dt>HEADER</dt>
             <dd>
-              denotes the size of this message in network byte order.
-              Set by the initiator.
-              <!-- FIXME: Is this not fixed-length once set by initiator?-->
-              Modified by processing peers when message contents change.
-            </dd>
-            <dt>MTYPE</dt>
-            <dd>
-              is the 16-bit message type. It is set by the initiator to
+              is the common message header. Its <tt>MTYPE</tt> field is set by the initiator to
               the value 147 in network byte order. Read-only.
             </dd>
             <dt>BTYPE</dt>
@@ -1793,7 +1803,7 @@ BEGIN
             <artwork name="" type="" align="left" alt=""><![CDATA[
 0     8     16    24    32    40    48    56
 +-----+-----+-----+-----+-----+-----+-----+-----+
-|  MSIZE    |   MTYPE   |        BTYPE          |
+|        HEADER         |        BTYPE          |
 +-----+-----+-----+-----+-----+-----+-----+-----+
 |  RESERVED |   FLAGS   | PUTPATH_L | GETPATH_L |
 +-----+-----+-----+-----+-----+-----+-----+-----+
@@ -1819,15 +1829,9 @@ BEGIN
           </figure>
           <t>where:</t>
           <dl>
-            <dt>MSIZE</dt>
-            <dd>
-              denotes the size of this message in network byte order.
-              Set by the initiator.
-              Updated by processing peers.
-            </dd>
-            <dt>MTYPE</dt>
+            <dt>HEADER</dt>
             <dd>
-              is the 16-bit message type. It must be set to
+              is the common message header. Its <tt>MTYPE</tt> field must be set to
               the value 148 in network byte order.
               Set by the initiator. Read-only.
             </dd>