3. TCPoXML

   This protocol MUST be implemented to be compliant with this RFC.  The
   DTD for this document type can be found in section 7.2.

3.1. TCP Description

   A number of items have changed from the original TCP specification.
   Bit-masks, where present have been converted into human-readable
   values.  Length and checksum and port values are present as decimal
   integers.

   To calculate the length and checksum fields of the TCP element, a
   canonicalized form of the element MUST be used as in section 2.1.

   An iterative method SHOULD be used to calculate checksums as in
   section 2.1.

   The payload element MUST be encoded as in section 2.1.

   The TCP offset element was expanded to a maximum of 255 from 16 to
   allow for the increased size of the header in XML.

   TCPoXML datagrams encapsulated by IPoXML MAY omit the <?xml?> header
   as well as the <!DOCTYPE> declaration.

3.2. Example Datagram

   The following is an example TCPoXML datagram with an empty payload:

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE tcp PUBLIC "-//IETF//DTD BLOAT 1.0 TCP//EN" "bloat.dtd">
   <tcp>
   <tcp.header>
   <src port="31415"/>
   <dest port="42424"/>
   <sequence number="322622954"/>
   <acknowledgement number="689715995"/>
   <offset number=""/>
   <reserved value="0"/>
   <control syn="1" ack="1"/>
   <window size="1"/>
   <urgent pointer="0"/>
   <checksum value="2988"/>
   <tcp.options>
   <tcp.end kind="0"/>
   </tcp.options>
   <padding pad="0"/>
   </tcp.header>
   <payload>
   </payload>
   </tcp>