Invalid Documents

• Valid:

  <GREETING>
  various random text but no markup
  </GREETING>
  
  

• Invalid: anything else including

  <GREETING>
    <sometag>various random text</sometag>
    <someEmptyTag/>
  </GREETING>
  
  

• or

  
  <GREETING>
   <GREETING>various random text</GREETING>
  </GREETING>