Can't filter for a null value in a custom view

Can't filter for a null value in a custom view

Hello.

I'm wanting to create a custom view to determine if a particular field has been populated.  Much to my chagrin, it seems that Books won't allow you to have a value of null as your search criteria giving you an error stating, "Please enter a value for 1".  Is there something I'm missing?  I can think of several reasons why you'd want to be able to do this.

Thanks,
Bryan