n.lastpost(): the set of XML nodes that match the last element of an XPath rooted at node n
lastpost() ：与根在节点 n上的 XPath的最后一个元素匹配的XML节点集
n.firstpos(): the set of XML nodes that match the first element of an XPath rooted at node n
firstpos() ：与根在节点n 上的XPath的第一个元素匹配的XML节点集
n.firstpos(): the set of XML nodes that match the first element of an XPath rooted at node n
firstpos() ：与根在节点n 上的XPath的第一个元素匹配的XML节点集
应用推荐