 files
  themselves are never modified.</li>
<li class="link ulchildlink"><span class="ulchildlinktext"><a href="../dev_ref/processing-pipeline-modules.html">DITA-OT processing modules</a></span><br />
The DITA-OT processing pipeline is implemented using Ant. Individual modules within the
Ant script are implemented in either Java or XSLT, depending on such factors as performance or
requirements for customization. Virtually all Ant and XSLT modules can be extended by adding a
plug-in to the toolkit; new Ant 