code: public String getRfsPrefix(String vfsName) {
  
          if (vfsName != null) {
              Iterator<CmsStaticExportRfsRule> it = m_rfsRules.iterator();
              while (it.hasNext()) {
                  CmsStaticExportRfsRule rule = it.next();
                  if (rule.getSource().matcher(vfsName).matches()) {
                      return rule.getRfsPrefix();
                  }
              }
          }
          return m_rfsPrefix;
      }
docs: Returns the prefix for exported links in the "real" file system.<p>
  
  The returned value will be a directory like prefix. The value is configured
  in the <code>opencms-importexport.xml</code> configuration file. An optimization
  of the configured value will be performed, where all relative path information is resolved
  (for example <code>/export/../static</code> will be resolved to <code>/export</code>.
  Moreover, if the configured path ends with a <code>/</code>, this will be cut off
  (for example <code>/export/</code> becomes <code>/export</code>.<p>
  
  This is resource name based, and based on the rfs-rules defined in the
  <code>opencms-importexport.xml</code> configuration file.<p>
  
  @param vfsName the name of the resource to export
  
  @return the prefix for exported links in the "real" file system
  
  @see #getExportPath(String)
  @see #getVfsPrefix()