When using the File Type wizard within a NB Module project, the first step provides the option of identifying your file
by an XML namespace.  It does not allow you to additionally choose the name of the root element in the document (that
is, you cannot specify a qualified name).  However, since NB does appear to accept fully qualified names in the MIME
resolver:

<!DOCTYPE MIME-resolver PUBLIC "-//NetBeans//DTD MIME Resolver 1.0//EN"
"http://www.netbeans.org/dtds/mime-resolver-1_0.dtd">
<MIME-resolver>
    <file>
        <ext name="xml"/>
        <resolver mime="text/ts+xml">
            <xml-rule>
                <element name="myRoot" ns="http://xml.kitfox.com/schema/tw/ts"/>
            </xml-rule>
        </resolver>
    </file>
</MIME-resolver>

It would be useful if the ability to specify a root element name could be exposed in the File Type wizard.