T2: Use of application/xml in payload container example

[Dan Weinreb <dlw@exceloncorp.com>]

In the Example of a Payload Container (section 7.4.1, line 505), the
Content-Type is shown as being "application/xml", whereas in the
Header Container Example (section 7.3.2, line 474), the Content-Type
is "text/xml".  Why?

The guideline for this distinction seems to be RFC 3023, section 3, bottom
of page 4:

   If an XML document -- that is, the unprocessed, source XML document
   -- is readable by casual users, text/xml is preferable to
   application/xml.  MIME user agents (and web user agents) that do not
   have explicit support for text/xml will treat it as text/plain, for
   example, by displaying the XML MIME entity as plain text.
   Application/xml is preferable when the XML MIME entity is unreadable
   by casual users.

That does not seem to explain what's going on in the examples.  It's
hard to see why the SOAP document in the header container is more
"textual" and less "applicationlike" than the Invoice document in the
payload container.

-- Dan