DTD到底有什么作用啊,高手指点
下面DTD定义中没有定义price元素,为什么在显示的时候不提示错误呢?
DTD在什么情况下起作用啊
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE publications [
<!ELEMENT publications (book+)>
<!ELEMENT book (title, author)>
<!ELEMENT title (#PCDATA)>
<!ELEMENT author (#PCDATA)>
]>
<publications>
<book>
<title>Mastering XHTML</title>
<author>Ed Tittel</author>
<price/>
</book>
</publications>