Ability to expand/un-expand xi:includes

[ajeanmahoney]

For example, be able to expand the following:

<xi:include href="https://bib.ietf.org/public/rfc/bibxml/reference.RFC.9110.xml"/>

to

<reference anchor="RFC9110" target="https://www.rfc-editor.org/info/rfc9110">
  <front>
    <title>HTTP Semantics</title>
    <author fullname="R. Fielding" initials="R." role="editor" surname="Fielding"/>
    <author fullname="M. Nottingham" initials="M." role="editor" surname="Nottingham"/>
    <author fullname="J. Reschke" initials="J." role="editor" surname="Reschke"/>
    <date month="June" year="2022"/>
    <abstract>
      <t>The Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document describes the overall architecture of HTTP, establishes common terminology, and defines aspects of the protocol that are shared by all versions. In this definition are core protocol elements, extensibility mechanisms, and the "http" and "https" Uniform Resource Identifier (URI) schemes.</t>
      <t>This document updates RFC 3864 and obsoletes RFCs 2818, 7231, 7232, 7233, 7235, 7538, 7615, 7694, and portions of 7230.</t>
    </abstract>
  </front>
  <seriesInfo name="STD" value="97"/>
  <seriesInfo name="RFC" value="9110"/>
  <seriesInfo name="DOI" value="10.17487/RFC9110"/>
</reference>

And be able to reduce full reference entries to an xi includes.

[JayDaley]

Should the reduce function check if any edits have been made in the local file that means it is now different to the contents of the remote file?

[ajeanmahoney]

If the expanded reference doesn't match the reference retrieved by the xi include, there should be a warning presented. This feature is supposed to be built into xml2rfc, but I'm not finding the issue that discusses it.