XPointer is a language that is used to link to fragments of XML documents. 

XPointer operating modes
Mode
XPointer can identify XML fragments.
XPointer can identify elements.
XPointer can identify schemes for namespaces.
XPointer can identify schemes for XPatch expressions.

XPointer frameworks and schemes
Name Description
XPointer framework Uses '#' to point to an element.
element() scheme A scheme used to search for elements.
xmlns() scheme A scheme used to search for data inside a namespace.
xpointer() scheme A scheme used to point to a location.