Type ErrorMessage = class

	class Function Fail();
	Begin
		return array(-1, '');
	End;

	class Function Ok();
	Begin
		return array(0, 'ok');
	End;

	class Function SheetExist(sheetName)
	Begin
		sheetName := ifString(sheetName) ?: ' ';
		return array(2, sheetName + ' already exists.');
	End;

	class Function SheetNotExist(sheetName)
	Begin
		sheetName := ifString(sheetName) ?: ' ';
		return array(3, sheetName + ' does not exist.');
	End;

	class Function DeleteFailure();
	Begin
		return array(4, 'Can not delete the last sheet.');
	End

End;
