>CREATE TABLE testtab (lvalue L null)
>APPEND BLANK
>REPLACE lvalue WITH .t.
>APPEND BLANK
>REPLACE lvalue WITH .f.
>APPEND BLANK
>REPLACE lvalue WITH null
>GO top
>SCAN NEXT 10
>   ? lvalue
>   ? ISNULL(lvalue)
>   ? (NVL(lvalue,.f.))
>   ?"-------------------"
>endscan
>