Docbook publishing for different target audiences

I like to have one docbook xml document that has content for several target audiences. Is there a filter that enables me to filter out the stuff only needed for "advanced" users?

The level attribute is invented by me to express what I have in mind.

 <?xml version="1.0"?>
 <book>  
   <title lang="en">Documentation</title>

   <chapter id="introduction" level="advanced">  
       <title>Introduction for advanced users</title>
   </chapter>

   <chapter id="introduction" level="basic">  
      <title>Introduction for basic users</title>
   </chapter>  

   <chapter id="ch1">
      <para level="basic">Just press the button</para>
      <para level="advanced">
           Go to preferences to set your
           needs and then start the process 
           by pressing the button.
      </para>
   </chapter>
</book>

DocBook does not have a level attribute. Perhaps you meant userlevel?

If you are using the DocBook XSL stylesheets to transform your documents, they have built-in support for profiling (conditional text). To use it you need to

1. use the profiling-enabled version of the stylesheet (e.g. use html/profile-docbook.xsl instead of the usual html/docbook.xsl), and

2. specify the attribute values you want to profile on via a parameter (e.g. set profile.userlevel to basic).

Chapter 26 of Bob Stayton's DocBook XSL: The Complete Guide has all the details.