anchor.diff:  // Root expression extension function called by other function.
   //
   vfrStatementExpression [UINT32 RootLevel, UINT32 ExpOpCount = 0] :
  -  << if ($RootLevel == 0) {mCIfrOpHdrIndex ++; if (mCIfrOpHdrIndex >= MAX_IFR_EXPRESSION_DEPTH) _PCATCH (VFR_RETURN_INVALID_PARAMETER, 0, "The depth of expression exceeds the max supported level 8!"); _CLEAR_SAVED_OPHDR ();} >>
  +                                                       <<
  +                                                          if ($RootLevel == 0) {
  +                                                            mCIfrOpHdrIndex ++;
  +                                                            if (mCIfrOpHdrIndex >= MAX_IFR_EXPRESSION_DEPTH) {
  +                                                              _PCATCH (VFR_RETURN_INVALID_PARAMETER, 0, "The depth of expression exceeds the max supported level 8!");
  +                                                            }
  +                                                            _INIT_OPHDR_COND ();
  +                                                          }
  +                                                       >>
     andTerm[$RootLevel, $ExpOpCount]
     (
       L:OR andTerm[$RootLevel, $ExpOpCount]              << $ExpOpCount++; CIfrOr OObj(L->getLine()); >>
  
positive.code:   UINT8               mCIfrOpHdrIndex;
    VOID                _SAVE_OPHDR_COND (IN CIfrOpHeader &, IN BOOLEAN, UINT32 LineNo = 0);
    VOID                _CLEAR_SAVED_OPHDR (VOID);
    BOOLEAN             _SET_SAVED_OPHDR_SCOPE (VOID);
  
  
  
negative.code: }
  
  VOID
  EfiVfrParser::_INIT_OPHDR_COND (
    VOID
    )
  {
    mCIfrOpHdr[mCIfrOpHdrIndex]       = NULL;
    mCIfrOpHdrLineNo[mCIfrOpHdrIndex] = 0;
  }
  
  VOID
  EfiVfrParser::_CLEAR_SAVED_OPHDR (
    VOID
    )
  {
    if (mCIfrOpHdr[mCIfrOpHdrIndex] != NULL) {
      delete mCIfrOpHdr[mCIfrOpHdrIndex];
      mCIfrOpHdr[mCIfrOpHdrIndex] = NULL;
    }
  }
  
  BOOLEAN
  