4. UDPoXML

   This protocol MUST be implemented to be compliant with this RFC.  The
   DTD for this document type can be found in section 7.3.

4.1. UDP Description

   A number of items have changed from the original UDP 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 UDP 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.

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

4.2. Example Datagram

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

   <?xml version="1.0" encoding="UTF-8"?>
   <!DOCTYPE udp PUBLIC "-//IETF//DTD BLOAT 1.0 UDP//EN" "bloat.dtd">
   <udp>
   <udp.header>
   <src port="31415"/>
   <dest port="42424"/>
   <udp.length value="143"/>
   <checksum value="2988"/>
   </udp.header>
   <payload>
   </payload>
   </udp>