As usual, Microsoft is very, if not extremely, weak on the specifications describing new features. So far, webslices are described by the following three documents:

I tried to find what's supposed to happen when more than one entry-title is specified. Are the entry-title text nodes all aggregated ? Nuts, nothing, nada, niente, que dalle.

All documents specify the expiration time in the RSS webslice feed as the endtime element in the http://www.microsoft.com/schemas/rss/monitoring/2007 namespace. Fine. Want to find more doc on that namespace ? Forget it. First, there is nothing behind that URL, well done Microsoft. Second no search engine is able to tell me more about it.

But that's not the worst. The worst is the following : I'm sure this changed over time. I'm almost sure the element was originally called expiration when the feature was submitted to eBay...

<?xml version="1.0"?><rss version="2.0" xmlns:mon="http://www.microsoft.com/schemas/rss/monitoring/2007" >
    <channel>
        ...
        <mon:expiration>2008-03-09T22:03:09Z</mon:expiration>
       ...

And of course, even if eBay webslices don't follow the current spec, IE8 deals with them correctly... Pfff.