                 Environments.
                </p>
            <p>
                    Environments are optional for non-transactional
                    applications that use the base API, but they are required for transactional
                    applications. (Of course, applications that use the
                    DPL always require the DPL.)
                </p>
            <p>
                    Environment usage is described in detail in 
                    <a class="xref" href="usingtxns.html"