code: def renderLink(self, relpath=""):
          
          # return from cache if available
          cachekey, html = self.checkCache('Link', relpath)
          if html is not None:
              return html
          # else regenerate
          html = CachingRenderer.renderLink(self, relpath)
          if self.headerfile is not None:
              html += """ (<A HREF="%s">header</A>)""" % quote_url(relpath + self.headerfile)
          # save to cache
          return self.writeCache(cachekey, html)
docs: renderLink() is called to render a link to the DP