anchor.diff:    begin
       if (OwnerCode[i] <= 'A') or (OwnerCode[i] >= 'Z') then
       begin
  -      aErrorMessage:= 'Owner code must be composed by 3 letters.';
  +      aErrorMessage:= SErrorWrongOwnerCode;
         exit;
       end;
     end;
  
positive.code: 
    if not (Length(aContainerCode) = 11) then
    begin
      aErrorMessage:= 'Wrong length. Must be 11 characters.';
      exit;
    end;
  
  
negative.code: 
  uses
    mMathUtility;
  
  resourcestring
    SErrorWrongLength = 'Wrong length. Must be 11 characters.';
    SErrorWrongOwnerCode = 'Owner code must be composed by 3 letters.';
    SErrorWrongCategoryIdentifier ='Wrong category identifier. Must be U or J or Z.';
    SErrorWrongSerialNumber = 'Only digits are allowed in serial number.';
    SErrorCheckDigitNotANumber = 'Check digit is not a digit.';
    SErrorWrongCheckDigit = 'Wrong check digit. It should be: ';
  
  
  // http://www.gvct.co.uk/2011/09/how-is-the-check-digit-of-a-container-calculated/
  // https://en.wikipedia.org/wiki/ISO_6346
  