On 2011 Jun 22, at 17:02, Jonathan Fletcher wrote:

> Not IsValid. That may give you a wrong answer under certain circumstances. The way described prior in this thread is correct.

Every table in every file I create starts off with the field "One". It's a calculation field set "= 1", and indexed. That's what I use as the target of all my IsEmpty or IsValid calculations. It's also useful with the "Count" function and when setting up all-to-all relationships. (I realize that the cross-product AxB relationship is a more elegant way to do so, but I've been using One=One since before cross products were available, and it still works just fine.)