It is clearly documented that when AutoYield = .T., The instance of Visual FoxPro processes pending Windows events between execution of each line of user program code.
Since it hasn't been proved as such, would you base your approach on a hunch that this is not true? If I understand corectly, Fabio is advising caution when dealing with this issue.

However, I don't use _TALLY in my code. IMO, RECCOUNT() or ALEN() is a much more worry-free aproach. My guess is that the purpose of _TALLY in VFP is to provide feeback *during* tallying operations. Thus, I wouldn't consider _TALLY a reliable value once the operation is completed.

>>>>>Hi,
>>>>>
>>>>>>
>>>>>I have done your test and it suggests that my *old* understanding is the correct one and Fabio's understanding is wrong! Agree?
>>>>>>
>>>>>
>>>>>Not really. As I mentioned it doesn't really prove anything. The fact that it doesn't appear to happen in a few thousand iterations doesn't mean that it will *never* happen. And if it *can* happen then any additonal lines between the 'SELECT' and the use of _tally would increase the risk.
>>>>>
>>>>
>>>>Exactly.
>>>
>>>How do you mean 'exactly'. What I observed with Viv's code is that the timer's Timer event did not even fire *once* during the loop! It is my hunch that the intended behavior of vfp is that the timer is not actively visited during execution of consequtive inputless commands. You suggest that this intention is not guaranteed everywhere/everytime. Can you write a program that gives support to your hunch?
>>
>>Hi Peter,
>>
>>I already lose a sea of time to understand all the bugs that I find.
>>I could write a program that tries to try that a Timer can also activate him
>>without DOEVENTS, but if I didn't succeed
>>it would not be a test some that this can never happen.
>>( even if the documentation wrote it, it would not be a certainty ! )
>>
>>If you want to risk and you are convinced that it never happens, not to save _TALLY;
>>the day that the data of your more important client will be corrupt
>>you will owe only to curse with yourself.
>>
>>Fabio
>
>I understand your pov. However, you have - this time - not been able to give proof of your statement. Being recognized for your insights, you are kind of a guru these days here and at least *some* people tend to believe whatever you say. In this case, that is not the wisest decision, imo. Hopefully, *others here* can confirm or contradict our pov's.