<!DOCTYPE doc
 [ <!ELEMENT doc - - (t|a)*>
   <!ELEMENT a   - - (#PCDATA)>
   <!ELEMENT t - - rcdata>
   <!ENTITY  hello "Hello">
   <!ENTITY  world "World &hello;">
 ]
>

<!-- coment -->

<doc>
<t>
This is rcdata &hello; & &world
</t>

<a>This is an a</a>

</doc>
