Here's the proposed XML structure for comments to NW entries:

<nwcomments nwentryurl="http: ....">
   <comment>
        <id>c123</id>
        <previd>c122</previd>
        <author>
                <name>Steph Troeth</name>
                <email>steph@unadorned.org</email>
                <url>http://unadorned.org/</url>
        </author>
        <content>
        I was on the bridge and I took this photograph of the river ....
        </content>
   </comment>
   <comment>
        <id>c124</id>
        <previd>c123</previd>
        <author>
                <name>Daisy Cow</name>
                <email>cow@unadorned.org</email>
                <url>http://unadorned.org/cow/</url>
        </author>
        <content>
         This area has very nice grass to eat. Right near a train line where I can watch the trains go too. Nice place to visit.
        </content>
   </comment>
</nwcomments>

The previd element is optional. This is used for threading purposes (based on issue raised by Delphine). If the previd doesn't exist, we assume we are looking at a new thread.