Try

  ... IIF(.T., myfunc(OtherField), NULL) 

>In a query similar to:
>
>

>select SomeField, MyFunc(OtherField) as CalculatedValue;
>  from MyTable;
>  into cursor Temp
>

>
>it may happen that MyFunc() returns .NULL. for some cases. If this happens, VFP informs me that the column doesn't accept NULL values.
>
>How do I make VFP allow null values? Of course, I could use NVL(...), but I do want NULL values in some cases, in order to know that there is some missing data.