<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hr SYSTEM "hr.dtd">
<!-- 人力资源管理系统 -->

<hr>
  <employee no="3309">
     <name>张三</name>
     <age>31</age>
     <salary>40000</salary>
     <department>
         <dname>会计部</dname>
         <address>大厦</address>
     </department>
  </employee>
<employee no="3308">
     <name>李四</name>
     <age>31</age>
     <salary>30000</salary>
     <department>
         <dname>销售部</dname>
         <address>大厦</address>
     </department>
  </employee>

</hr>

DTD：

<?xml version="1.0" encoding="UTF-8"?>

<!ELEMENT hr (employee+)>

<!ELEMENT employee (name,age,salary,department)>

<!ATTLIST employee no CDATA "">

<!ELEMENT name (#PCDATA)>

<!ELEMENT age (#PCDATA)>

<!ELEMENT salary (#PCDATA)>

<!ELEMENT department (dname,address)>

<!ELEMENT dname (#PCDATA)>

<!ELEMENT address (#PCDATA)>

报错：