Sometimes it is more useful to point to more specific content. For example, let's say that we want to link to the third item in a particular list, or to the second sentence of the fifth paragraph. This is easy with XPointer.
一般来说，链接到具体内容的这一功能用途更为广泛。比如说，要链接到一个列表中的第三个项目、或第五段中的第二句话，这时，使用XPointer就非常容易了。

If the hyperlink points to an XML document, we can add an XPointer part after the URL in the xlink:href attribute, to navigate (with an XPath expression) to a specific place in the document.
链接指向XML文件时，我们可以在xlink:href属性值URL之后加一个XPointer字段，它就可以直接（利用XPath表达式）导向文件中的特定位置。

For example, in the example below we use XPointer to point to the fifth item in a list with a unique id of "rock":

看下例，用XPointer导向列表中含有"rock"这个id的第五子项：
href="http://www.example.com/cdlist.xml#id('rock').child(5,item)"