Thanks for the feedback Sergey. I tested this in an EXE and noted that I can't use MODI FORM at all. I changed approach to using a temporary timer object.

>>Hi all,
>>
>>I am modifying a form programmatically using MODI FORM myForm NOWAIT. I can't seem to close the form by calling SYS(1600,"_MFI_CLOSE","_MFILE"). Is this not allowed?
>>
>>TIA.
>
>Try

KEYBOARD "{CTRL+W}"