These could be used for automatically detecting changes. They could also
be used to transparently cache ordinary URL pages at any node in the net
without needing URNs.
FRESH UNTIL is a conservative estimate of update frequency.
If a page is modified before its old FRESH UNTIL date has expired, the node
must notify sites that have it cached, or risk users fetching the old
version.
Roedy@bix.com
-30-