wicket-core/src/test/java/org/apache/wicket/markup/MarkupInheritanceBase_4.html

  base: before
  <!-- note: extension and base can not have equals ids like e.g. "label" -->
  extension: 1 <span wicket:id="label1">Label 1</span> extension: 2
  <wicket:child/>
  extension: 1 <a href="#" wicket:id="link">increment</a> extension: 2
  base: after