When overridden in a derived class, compares the base Uniform Resource Identifiers (URIs) of two documents based upon the order the documents were loaded by the XSLT processor (that is, the System.Xml.Xsl.XslTransform class).
An integer value describing the relative order of the two base URIs: -1 if baseUri occurs before nextbaseUri; 0 if the two base URIs are identical; and 1 if baseUri occurs after nextbaseUri.
This method supports the XSLT document() function which specifies that nodes selected across multiple documents are always returned in the same order.
The order is implementation-specific.