IsExclusive works only in current DS, so it really doesn't help to find, if file could be used exclusively. The best method is to use Error Handler and trap this error. I have a special OpenTble function, which handles that...

>Hi,
>
>Thank, BTW, the error message happened only when I open the backup file
>in shared mode with VFP3 to test whether it can detect other using it too.
>When my application run to the ISEXCLUSIVE function, the error will prompt up.
>
>
>>>Hi,
>>>
>>>It seem like the ISEXCLUSIVE function is causing the message.
>>>When you refer to low-level function, could you show me how to
>>>do that
>>>

>>lnHandle = fopen('backup.dbf',12)
>>if m.lnHandle > 0 && File could be used exclusive
>>   fclose(m.lnHandle)
>>   ...
>>endif

>>
>>There is a slight chance of failing, but the possibility is too small to make it into consideration...