<!ELEMENT person (address,age,sex,father+,children*,couple?,ismarried?)>
<!ATTLIST person name NMTOKEN #REQUIRED>
<!ELEMENT address (#PCDATA)>
<!ELEMENT age (#PCDATA)>
<!ELEMENT sex (#PCDATA)>
<!ELEMENT father (fathername)>
<!ELEMENT fathername (#PCDATA)>
<!ELEMENT children (childname)>
<!ELEMENT childname (#PCDATA)>
<!ELEMENT couple (couplename)>
<!ELEMENT couplename (#PCDATA)>
<!ELEMENT ismarried EMPTY>
在每个element声明之后要加一个空格
<!ATTLIST person name NMTOKEN #REQUIRED>
<!ELEMENT address (#PCDATA)>
<!ELEMENT age (#PCDATA)>
<!ELEMENT sex (#PCDATA)>
<!ELEMENT father (fathername)>
<!ELEMENT fathername (#PCDATA)>
<!ELEMENT children (childname)>
<!ELEMENT childname (#PCDATA)>
<!ELEMENT couple (couplename)>
<!ELEMENT couplename (#PCDATA)>
<!ELEMENT ismarried EMPTY>
在每个element声明之后要加一个空格
<!ATTLIST person name NMTOKEN #REQUIRED>
<!ELEMENT address (#PCDATA)>
<!ELEMENT age (#PCDATA)>
<!ELEMENT sex (#PCDATA)>
<!ELEMENT father (fathername)>
<!ELEMENT fathername (#PCDATA)>
<!ELEMENT children (childname)>
<!ELEMENT childname (#PCDATA)>
<!ELEMENT couple (couplename)>
<!ELEMENT couplename (#PCDATA)>
<!ELEMENT ismarried EMPTY>
在每个element声明之后要加一个空格