Perhaps I wasn't clear in describing what the CHANGED tag does. It does not
mark the document as changed for purposes of retrieval. It marks sections of
a document as changed for purposes of showing a reader where revisions from
the previous version have been made.
This is quite commonly used in technical documentation. Typically the changed
areas are marked with "revision bars" which are vertical lines in the left
margin next to the changed lines.
Relay Technology, Inc.