签名领域是被无符号整数(Ui4)所标记,但是当它被Com 接口所询问时，它要作为VT_I4型返回，VT_I4是一种标记形式（VT_UI4），这个需要-Field Signature is marked as unsigned integer (ui4), but when it is quered from COM interface it is returned as VT_I4 which is signed type