Re: last-seen & server ability to indicate "Never cache"?

Ari Luotonen (
Thu, 10 Mar 1994 21:35:57 --100

First, if we have If-Modified-Since: header, we naturally
don't return an even older version -- only if we have a newer

Second, yes, date is in GMT. All HTTP times are in GMT, and
I made a reference saying that the format is the same as for
Date: field and assumed that would be clear.

So what John Ellson said about giving exactly the same string
back in If-Modified-Since header as we got from Last-Modified
is valid, and in that sense we don't have to care about the
time zone, but since (for other reasons) Last-Modified is spec'd
to be GMT so is If-Modified-Since.

> If we want to do caching well, we also need some way to indicate
> that a document should never be cached, e.g. the output from some
> scripts will ALWAYS be new documents.

Use Expires: with the current time.

> PS. Where is the latest HTTP spec available from?

-- Cheers, Ari --