xpath - confusion with Node Set Function - 'ID'

Question

Function: node-set id(object)

When the argument to id is of type node-set, then the result is the union of the result of applying id to the string-value of each of the nodes in the argument node-set.

I didn't get the above lines from the doc. May I have one example to understand the same ?

Thanks

Answer 1

当然

假设您的文档使用属性 idref="AB C" 来包含对具有 id="A"、id="B" 和 id="C" 的节点的引用。

然后id(//@idref)将选择文档中任何位置的任何@idref 属性中引用的具有id 的所有节点。