My guess is that oApp is a global variable and as such is always available. The 'ThisForm' is only available to the code executed in the context of a form.

>I've been doing this by trial and error but there must be some logic here
>
>This works:
>
> "EXEC sp_Update_Atmservice ?ln_transid, ?lc_orderstatus, ?lc_notes, ?oApp.gc_user"
>
>This does not work:
>
> "EXEC sp_Update_Atmservice ?ln_transid, ?thisform.lc_orderstatus, ?lc_notes, ?oApp.gc_user"
>
>I'm wondering why the property oApp.gc_user is OK and the property thisform.lc_orderstatus is not.Both are character properties with character values in them.
>
>In order to get the second line to work, I have to move thisform.lc_orderstatus into a memory variable and pass that thru.
>
>What is the logic here?