--- a/os.xmlf
+++ b/os.xmlf
@@ -1,13 +1,9 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!DOCTYPE chapter [
-<!ENTITY % eclent SYSTEM "ecl.ent">
-%eclent;
-]>
-<book xmlns="http://docbook.org/ns/docbook" version="5.0" xml:lang="en">
-<chapter xml:id="ext.os">
+<?xml version="1.0"?><!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.4//EN" "http://www.oasis-open.org/docbook/xml/4.4/docbookx.dtd">
+<book lang="en">
+<chapter id="ext.os">
  <title>Operating System Interface</title>
 
- <section xml:id="ext.os.processes">
+ <section id="ext.os.processes">
   <title>Processes</title>
 
   <para>&ECL; provides several facilities for invoking and communicating with
@@ -18,19 +14,19 @@
   program and manipulate it while it runs on the background.</para>
  </section>
 
- <section xml:id="ext.os.command-line">
+ <section id="ext.os.command-line">
   <title>Command line arguments</title>
 
   <para></para>
  </section>
 
- <section xml:id="ext.os.dict">
+ <section id="ext.os.dict">
   <title>OS Reference</title>
 
-  <xi:include xmlns:xi="http://www.w3.org/2001/XInclude" href="ref_os.xmlf" xpointer="os.dict"/>
+  &RefOS;
 
  </section>
-</chapter>
+ </chapter>
 </book>
 <!-- Keep this comment at the end of the file
       Local variables: