Some facts about XPath

What is XPath, where did it come from ?

• XPath is a language for finding information in an XML document
• XPath uses path expressions to select nodes or node-sets in an XML document.



taken from here



• XPath is part of XSLT and XQuerry. If you want to use XSLT or XQuerry you will have to learn XPath
• In XPath, there are seven kinds of nodes: 
• element, 
• attribute, 
• text, 
• namespace, 
• processing-instruction, 
• comment, and 
• document nodes.

Some terms have to be known

• XML documents are treated as trees of nodes. The topmost element of the tree is called the root element.
• Atomic values are nodes with no children or parent.
• Items are atomic values or nodes.
• Each element and attribute has one parent.
• Element nodes may have zero, one or more children.
• Nodes that have the same parent are called siblings.
• Ancestores of a node are node's parent, parent's parent, etc.
• Descendants of a node are node's children, children's children, etc.

Selection nodes

• XPath uses path expressions to select nodes in an XML document. 

nodename	Selects all nodes with the name "nodename"
/	Selects from the root node
//	Selects nodes in the document from the current node that match the selection no matter where they are
.	Selects the current node
..	Selects the parent of the current node
@	Selects attributes