[Zope] KeyError with non-existant _[variables]

I'm getting a KeyError trying to render non-existant _[variables] <dtml-var "_[variable]" null="triedthis" missing="triedthistoo"> say variable == firstname, but firstname is not a variable- I'd like to set it to null and proceed- { I'm using this to build a generic SQL edit form based on column names and keyed input } Chas. <c3w@ISP.NET> ISP Networks, Inc.