<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE superheroes [
  <!ELEMENT superheroes ANY>
  <!ELEMENT superheroe (#PCDATA)>
]>
<superheroes>
  <superheroe>Hulk</superheroe>
  <superheroe>Thor</superheroe>
  <superheroe>Iron Man</superheroe>
</superheroes>