[Zope] <dtml-in> sorting problem

Hello all, Here's my problem: I want to sort a list of objects on a property that not all items have. So I'm doing this: <dtml-in sort=someProperty,someOtherProperty> The problem is that those items that have a blank someProperty are listed first, when I want them at the bottom of the list. I don't want to reverse the entire sort order, I just want blank values treated as being larger than any other value. Any suggestions? Michael Bernstein.