[Zope] lists

I have a group of checkboxes on a site that I want to parse into an email. I've been trying to use dtml-in to iterate through the checked boxes, but if they only check one box then it's not a list anymore and dtml-in barfs. Is the only solution to trap an error and render it as a var in the except? like this: <dtml-try> <dtml-in checkbox> <dtml-var sequence-item> </dtml-in> <dtml-except> <dtml-var checkbox> </dtml-try> or is there a more elegant way to do this? TIA Rick