dd>
<p>
                Optionally specifies a directory to apply as a prefix to all relative
                file paths in the script file.
              </p>
<p>
                You may wish to do this to reduce typing of pathnames, and/or where
                the paths can't be located relative to the script file location,
                typically if the headers are in the Boost trunk, but the script file
                is in Boost sandbox.
              </p>
<p>
                For Boost standard lib