<!DOCTYPE a [

<!ELEMENT a (b | (c, d)* | (e, f)+ | g?)>
<!ELEMENT b (#PCDATA | a)*>
<!ELEMENT c EMPTY>
<!ELEMENT d ANY>
<!ELEMENT e EMPTY>
<!ELEMENT f EMPTY>
<!ELEMENT g EMPTY>

<!ATTLIST a u CDATA #IMPLIED
            v NMTOKEN "huhu"
            w (q|p)   #REQUIRED
            x NOTATION (n1|n2) "n1"
            y ENTITY #IMPLIED>

<!NOTATION n1 SYSTEM "/bin/n1-processor">
<!NOTATION n2 SYSTEM "/bin/n2-processor">

<!ENTITY u1 SYSTEM "file-u1" NDATA n1>
<!ENTITY u2 SYSTEM "file-u2" NDATA n2>

<!-- comment 1 -->
<?pi1 args ...?>
]>

<!-- comment 2 -->
<a u="1" w="q" x="n2">
  <!-- comment 3 -->
  <b>
    <?pi2 args ...?>
    This is text!
    <a w="p" y="u1">
      <c/>
      <d/>
    </a>
  </b>
  <!-- comment 4 -->
</a>

<!-- comment 5 -->
<?pi3 args ...?>
<!-- comment 6 -->