我这样写xml文件是否正确，在网页里面打不开，校验的也打不开

[Worry_Echo]

<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE exam[
<!ELEMENT exam ANY>
<!ELEMENT student (name,location,grade)>
<!ELEMENT name (#PCDATA)>
<!ELEMENT location (#PCDATA)>
<!ELEMENT grade (#PCDATA)>
<!ATTLIST student idcard ID #REQUIRED exanmid ID #REQUIRED>

]>
<exam>
<student idcard="1" examid="123">
<name>张三</name>
<location>成都</location>
<grade>80</grade>
</student>
</exam>

[Worry_Echo]

如果还需要一个id就得重新在写一个ATTLIST 对吗

[hookee]

ATTLIST 的 ID只能一个

<?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE exam[
 <!ELEMENT exam ANY>
 <!ELEMENT student (name,location,grade)>
 <!ELEMENT name (#PCDATA)>
 <!ELEMENT location (#PCDATA)>
 <!ELEMENT grade (#PCDATA)>
 <!ATTLIST student idcard ID #REQUIRED exanmid CDATA #REQUIRED>
 ]>
 <exam>
	 <student idcard="1" examid="123">
		 <name>张三</name>
		 <location>成都</location>
		 <grade>80</grade>
	 </student>
 </exam>