1 <?xml version="1.0"?> 2 <!DOCTYPE a [ 3 <!ELEMENT a (#PCDATA | b | c)*> 4 <!ELEMENT b (#PCDATA)> 5 <!ELEMENT c (#PCDATA)> 6 <!ELEMENT a (#PCDATA | b | c)*> 7 ]> 8 <a> violates [ VC: Unique Element Type Declaration ] </a> 9
