<!DOCTYPE exa [
<!ELEMENT exa (a|b)*>
<!ELEMENT a ((b|c)*,b,(b|c),(b|c),(b|c),(b|c),(b|c),(b|c),(b|c))>
<!ELEMENT b ANY>
<!ELEMENT c ANY>
]>
<exa>
<!-- this comment has a -- in it. -->
<a/>
<b>
this element contains a "]]>" sequence
</b>
</exa>