<?xml version="1.0" standalone="no"?>
<!DOCTYPE DOCUMENT [
   <!ELEMENT DOCUMENT (TITLE, SIGNATURE)>
   <!ELEMENT TITLE (#PCDATA)>
   <!ELEMENT COPYRIGHT (#PCDATA)>
   <!ELEMENT EMAIL (#PCDATA)>
   <!ELEMENT SIGNATURE (COPYRIGHT, EMAIL)>
   <!ENTITY SIG SYSTEM 
      "http://metalab.unc.edu/xml/signature.xml">
]>
<DOCUMENT>
  <TITLE>Entity references</TITLE>
  &SIG;
</DOCUMENT>
