Andy,
Agreed. Unfortunately, most aggregators don't. So, I would advise
against xml:base and relative URLs. In fact, all of the RSS
validators [1], last I remember, will reject any such cuteness,
including my own Schematron-based validator [2].
Thanks,

Randy
http://www.kbcafe.com

[1] http://feedvalidator.org
[1] http://rss.scripting.com/
[2] http://www.kbcafe.com/rss/?guid=20041030111147

--- In "Houghton,Andrew" <houghtoa@o...> wrote:
> Actually, there is no "good reason" why aggregators should not
> support relative URL's. It's not that difficult and the
> argument given about re-aggregation is weak at best. An
> aggregator should be able to detect an appropriate xml:base
> attribute and construct an absolute URL from the relative URL.
> If they pass the feed along, they can pass the appropriate
> xml:base attribute or the absolute URL's they constructed.
>
>
> Andy.