It works with a slight addition to handle the blenks

set filter to ! (isnull(Zip) or transform(val(Zip), '@L 99999') == Zip or isblank(zip))

I had forgotten that transform includes a format provision,

Thanks


>Maybe
>
>

set filter to ! (isnull(ZipCode) or transform(val(ZipCode), '@L 99999') == ZipCode)

>
>>the following code:
>>
>>set filter to ! transform(val(ZipCode)) == ZipCode
>>
>>reveals blanks and zipcodes beginning with 0 as well as those containing alpha characters.