The HTTP documentation mentions the Expires: header which "Gives the date
after which the information ceases to be valid and should be retrieved
again" to "allow for the periodic refreshing of displays of volitile
data".
Some clients are now starting to support the Expires header, but I know of
none that will automatically refresh without user intervention. If they
do then there is a need for a second header: one that tells the client
that the document will expire at some given time - but don't bother
getting it again.
Mark
Mark J Cox ---------------------- URL:http://www.eia.brad.ac.uk/mark.html
University of Bradford, UK --------------- tel +44.1274.384070/fax 391333