creating rss in xsl

Long story short: I have a folder with .xml files (news1.xml, news2.xml, etc) which look like
<root>
    <news>
        <category>Sports (or politics, music, etc)
        </category>
......
    </news>
</root>

I need to do an rss for the different categories of the news. So i would have a sports.xml where all the news with category=sport would be, a politics.xml with the news from politics, etc
Now, sorting the news is not the problem. But I'm not sure how should the sports.xml, politics.xml files should be "created"?? Should I create the files manually and after that populate them with the data I want or should this be done in xsl? this is the first time I have to create an rss and I'm a little unsure on how to do it.Thank you!




 
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