code: private void executeFallbacks(
            TransformerImpl transformer)
              throws TransformerException
    {
      for (ElemTemplateElement child = m_firstChild; child != null;
               child = child.m_nextSibling)
      {
        if (child.getXSLToken() == Constants.ELEMNAME_FALLBACK)
        {
          try
          {
            transformer.pushElemTemplateElement(child);
            ((ElemFallback) child).executeFallback(transformer);
          }
          finally
          {
            transformer.popElemTemplateElement();
          }
        }
      }
  
    }
docs: Execute the fallbacks when an extension is not available.
  
  @param transformer non-null reference to the the current transform-time state.
  
  @throws TransformerException