<?xml version="1.0"?>
<!DOCTYPE a SYSTEM "dtds/a.dtd" [
<!ELEMENT a (#PCDATA | b | c)*>
<!ELEMENT b (#PCDATA)>
<!ELEMENT c (#PCDATA)>
]>
<a> violates [ VC: Unique Element Type Declaration ] </a>
<?xml version="1.0"?>
<!DOCTYPE a SYSTEM "dtds/a.dtd" [
<!ELEMENT a (#PCDATA | b | c)*>
<!ELEMENT b (#PCDATA)>
<!ELEMENT c (#PCDATA)>
]>
<a> violates [ VC: Unique Element Type Declaration ] </a>