Goal: Convert a RDDL document to pure XHTML.
RDDL is
 just an XHTML Basic document in which there's one extra element:
 rddl:resource 
 which can appear anywhere a p 
 element can appear, and can contain anything a 
 div element can contain. 
The customary rddl prefix is mapped to the 
 http://www.rddl.org/ namespace URL:
 
<rddl:resource id="rec-xhtml"
        xlink:title="W3C REC XHTML"
        xlink:role="http://www.w3.org/1999/xhtml"
        xlink:arcrole="http://www.rddl.org/purposes#reference"
        xlink:href="http://www.w3.org/tr/xhtml1"
        >
<li><a href="http://www.w3.org/tr/xhtml1">W3C XHTML 1.0</a></li>
</rddl:resource>
The program needs to throw away the 
<rddl:resource> start-tag and </rddl:resource>
 end-tag while leaving everything else intact.