Encapsulates the multiple extant versions of the DIG protocol, which have
different expectations as to namespaces, XML encodings, and other variables. This
allows us to parameterise the DIG interface to different DIG enabled tools.
author: Ian Dickinson, HP Labs (email) version: Release @release@ ($Id: DIGProfile.java,v 1.12 2008/01/02 12:07:11 andy_seaborne Exp $)