For Numeric data type you could use ISBLANK(), but for Integer.. I don't know.

>Well, I'm just gonna avoid using Zeros for data - but at the moment I'd like to avoid modifying data by hand. Since they're not nulls, any way to differentiate betwixt zeros and nothin?
>
>>>My table includes a numeric field with data from 0 to 2 - but it also has empty fields. I'd like to increase all the numeric entries by one, but I don't want to change the blank values.
>>>
>>>EMPTY() does not seem to differentiate between zeros and blanks, and the blanks don't seem to be nulls. LEN(STR(field)) doesn't do it, either!
>>>
>>>How can I filter out the blank records from the replacement?
>>>
>>>TIA
>>
>>You may better use .NULL. to get true and safe difference.