tforms.</p>

  <h3 id="req_trac">Trac</h3>

  <p>The use of <a href="http://trac.edgewall.org/">Trac</a> is entirely
  optional (although highly recommended if you are using Subversion). At the
  Met Office we are currently using version 0.9.6.</p>

  <h3 id="req_other">Other Requirements</h3>

  <p>The <code>fcm diff --graphical</code> and <code>fcm conflicts</code>
  commands require <a href="http://furius.ca/xxdiff/">xxdiff</a>. At the Met
  Office we are currently using version 3.1.</p>

  <p>The build 