>>>>Hi, all! Please answer which function can determinate does object (in my sample form) exists or not. Thank you. Andrew
>>>
>>>If you're checking on a object in a form, use the PEMSTATUS() function. If you want to know if a form exists, you can check the _SCREEN.FORMS collection.
>>
>>Also you can check if
>>
>>TYPE("thisform.myobject")= "O"
>>
>>and check for !ISNULL(thisform.myobject)
>
>I can see the need to check ISNULL() for an object variable pointing to an object that may have been destroyed. But how would THISFORM.myobject become .NULL. if it existed?

It may look excessive, and probably it is, but truly speaking thisform.myobject syntax by mistake may point to the form property which contained the object reference and was reset to .NULL.
Theoretical scenario: It is possible to remove the form object, then add the property with the same name, assign object to it and reset property to .NULL.

Now you have

TYPE("_screen.activeform.text1") = "O"
and _screen.activeform.text1 equals to .NULL.

Voila! :)

Oh, well, that may be an overkill... :)