>It really depends on whether or not you're returning a value, or retrieving a value from the form. Then, you really need to check its state.
>
>BTW, I don't think that the first line in the IF statement ever will ever evaluate to anything other than null. You need to re-write it to something like

IF UPPER(TYPE('oe_custcv'))="O" .AND. NOT ISNULL(Oe_custcv)

FWIW, there is also no need to check with ISNULL(). I the form is not an Object type, then TYPE function returns "U". If the return value is "O", then ISNULL will always be false.