title: DocBook 5: How do I do variable substitution to replace ${version} by a value?
body: <p>While writing a large manual in DocBook 5 (which uses an XSD, not DTD), I need to mention the version name in many places. For example, the name of distribution zip includes the version name. That version name changes constantly, so I 'd like to use a variable for that.</p>
  
  <p>How do I do variable substitution in DocBook 5 (which uses an XSD, not DTD)?</p>