>>>Which is what I expected
>>>
>>>If the expr is null it takes the else part of the iif()
>>>
>>Great thought about NULL.
>
>Yep, but NULL is nether .T. neither .F.
>I would use NVL() instead of IIF() :-)

Right, but good that Gregory brought nulls into the picture since often we forget to check logical expression for NULL.

In other words, the original statement could have been written as

Condition = llExp IS NOT NULL and llExp

or

Condtion = llExp IS NULL OR llExp

Depending on what do we want to check.