xml base

This specifies the base URL for any relative URLs. When nested, the declaration in a descendant element can be appended to that in the ancestor element. xml:base is also recognized in XLink, XPointer, and XInclude.

<?xml version="1.0" encoding="UTF-8"?>
<bookslist xml:base="http://GoldenBookstore.com">
   <gb:book xmlns:gb="http://GoldenBookstore.com" xml:base="/branch1">
      <title>Harry Potter</title>
   </gb:book>
</bookslist>