function _GetArraySep($s_sep)
 {
     //
     // check for cached (previously calculated) value
     //
     if ($s_sep !== $this->_sArraySep) {
         $this->_sArraySep = $s_sep;
         $this->_sArraySepValue = FieldManager::Substitute($this->_sArraySep);
     }
     return $this->_sArraySepValue;
 }