How should a feed tell people it's gone?

["Bill Kearney" <wkearney99@hotmail.com>]

Hi all,

I've been noticing more than a few feeds have gone offline lately.  A nearly
equal number seem to come online so this isn't troubling.  What I'm
wondering, however, is what thoughts have been given toward aiding the feed
consumer when a feed dies?

There appears to be no standardized mechanism for a feed to indicate it's
going to go offline.  I've noticed that some readers don't even bring this
to the users' attention.  Is it worth considering some sort of trigger that
a feed could contain that would aid the reader program?

Thanks,
Bill Kearney