JAXB looking for tag type rather than tag name?

Question

Hi everyone.
I'm trying to use JAXB to load an xml file, [http://www.unimod.org/xml/unimod.xml|http://www.unimod.org/xml/unimod.xml] . The schema is at [http://www.unimod.org/xmlns/schema/unimod_2/unimod_2.xsd|http://www.unimod.org/xmlns/schema/unimod_2/unimod_2.xsd] . I generate my classes using xjc with no problems. My unmarshalling code is simple enough:
try {
    JAXBContext ctx = JAXBContext.newInstance(new Class[] {UnimodT.class});
    Unmarshaller um = ctx.createUnmarshaller();
    return (UnimodT) um.unmarshal(is);
} catch (JAXBException ex) {
}At first I got an exception saying that unimod (the top-level tag) is unexpected and that the expected element is (none). I solved this by adding the @XmlRootElement tag into my UnimodT class. Now I am getting a javax.xml.bind.UnmarshalException :
"unexpected element (uri:"http://www.unimod.org/xmlns/schema/unimod_2", local:"unimod"). Expected elements are <{http://www.unimod.org/xmlns/schema/unimod_2}unimodT>"
I am guessing this means that it is looking for a <unimodT> tag while the actual tag name is <unimod>.
This is how the xml file starts:
<umod:unimod xsi:schemaLocation="http://www.unimod.org/xmlns/schema/unimod_2 http://www.unimod.org/xmlns/schema/unimod_2/unimod_2.xsd" majorVersion="2" minorVersion="0">
    <umod:elements>
          ....and here is the fragment from the xml schema defining the root element:
     <xs:element name="unimod" type="umod:unimod_t">Other guesses I am having are:
1) Maybe I should do something with the namespace, "umod"?
2) The underscore in the type name is confusing xjc?
Please help if you can. I am guessing it is something simple but I have no idea what.

Answer 1

I seem to have solved my problem by adding the namespace and name of the tag on the XmlRootElement annotation:
@XmlRootElement(name="unimod",namespace="http://www.unimod.org/xmlns/schema/unimod_2")however I still don't understand
1) why it's not enough to specify the name of the tag in the @XmlType annotation
2) why the @XmlRootElement tag was not specified automatically
I guess I should just be happy that it works now.