INFORMALEXAMPLE:
Content Model Declaration

Content Rule

((calloutlist|glosslist|itemizedlist|orderedlist|segmentedlist|simplelist|
  variablelist|literallayout|programlisting|programlistingco|screen|screenco|
  screenshot|synopsis|cmdsynopsis|funcsynopsis|classsynopsis|fieldsynopsis|
  constructorsynopsis|destructorsynopsis|methodsynopsis|formalpara|para|
  simpara|
  (address|blockquote|mediaobject|mediaobjectco|informalequation|
   informalexample|informalfigure|informaltable)|indexterm)+)