Ver ejemplos XPath en:
http://www.w3schools.com/xpath/xpath_syntax.asp
The XSL <xsl:for-each> element can be used to select every XML element of a specified node-set:
An XSL style sheet consists of one or more set of rules that are called templates.
Each template contains rules to apply when a specified node is matched.
<xsl:template> element is used to build templates.
The match attribute is used to associate a template with an XML element. The match attribute can also be used to define a template for the entire XML document. The value of the match attribute is an XPath expression (i.e. match="/" defines the whole document).
select attribute, the xsl:apply-templates instruction processes all of the children of the current node, including text nodes