XPath cheatsheet
/bookRoot book element only
//bookAll book elements anywhere
book/titleDirect title children of book
book[@lang='en']Books whose lang attribute equals en
book[1]First book child
book[position()<3]First two book children
count(//book)Number of book elements
//book/@idAll id attributes on books
text()Text node of the current element
name(.)Name of the current element