Migrate asx file to silverlight playlist. Are <starttime> and <duration> functions available?

Question

I'm pretty new to windows media player and silverlight. I have existing code that generates asx file and plays it with windows media player. I would like to migrate it to silverlight for it's cross-platform and cross-browser feature.

I started with open video player and tried to have silverlight play asx file. It doesn't work out too well and I heard it doesn't really support multiple tag which I really need for my project.

One of the source that silverlight accept is playlist. I tried to convert the asx file to the Windows playlist xml from Expression-Encoder (without actually encode the media using Expression-Encoder). The asx source looks like this:

 <ASX VERSION="3.0">
    <Title>title</Title>
    <Entry>
        <Title>entry1</Title>
        <Ref href="http://somefile.wmv" />
        <STARTTIME VALUE="0:52:00" />
        <Duration value = "00:15:00" />
    </Entry>
</ASX>

And the playlist xml would look like:

<playList>
    <playListItems>
        <playListItem title="1st video" mediaSource="http://firstvideo.wmv" ></playListItem>
        <playListItem title="2st video" mediaSource="http://secondvideo.wmv" ></playListItem>
    </playListItems>
</playList>

I have problem finding more information on the playlist. Maybe I just don't know the right keywords to use. Does anyone have idea if silverlight playlist can do and like asx does? If yes, where can I find more information? Thank you very much!