this is a partial xpath.
http://www.softwaretestinghelp.com/using-selenium-xpath-and-other-locators-selenium-tutorial-5/
http://docs.oracle.com/javaee/1.4/tutorial/doc/JAXPXSLT3.html
i didnt find answers to the question in the links mentioned. Nowhere it is mentioned 2 // signs in xpaths. Please let us know the answer to this.