You already know how to link XML documents together with XLink, and isolate specific nodes or node collections with XPath. Now uncover the third and final piece of the XML linking jigsaw - XPointer, an experimental technology from the W3C, which allows you to create XML links to specific points or ranges within an XML document.
The range() function is great for times when you need to define a range which begins and ends with the same element. However, for situations which require more asymmetric ranges, XPointer also offers the range-to() function, which allows link authors greater flexibility when defining ranges.
The range-to() function creates a range beginning with the context node and ending with the location set specified as an argument to the range-to() function. For example, the following XPointer
defines a range beginning at the opening "cast" element and ending at the closing
It's also possible to identify points and ranges within character data - the string-range() function scans a specified location for a match to a user-specified string, and returns a range containing the result. So, the following XPointer
xpointer(string-range(//cast, "Patrick Stewart"))
would return a range enclosing the string "Patrick Stewart" from the "cast" element.
If the XML document above contained more than one "cast" element matching the specified string, the string-range() function would return multiple ranges, one for each match.
It's possible to further constrain the range returned by specifying two additional arguments to the string-range() function - an offset to push forward the starting point of the range, and a length constraint to move back the ending point. So a modification of the XPointer above to