Sequences

    <name>
      <first_name>Elliotte</first_name> 
      <middle_name>Rusty</middle_name> 
      <last_name>Harold</last_name>
    </name>

• Separate multiple required child elements with commas; e.g.

  <!ELEMENT name (first_name, middle_name, last_name)>
  

• A list of child elements separated by commas is called a sequence