<!ELEMENT root (level1, level1a) >

<!ATTLIST root
    xsi:noNamespaceSchemaLocation CDATA #REQUIRED
    xmlns:xsi CDATA #REQUIRED
    attBoth  CDATA #REQUIRED
    attDTD  CDATA #REQUIRED
>

<!ELEMENT level1 (#PCDATA) >
<!ELEMENT level1a (#PCDATA) >