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

[Chas Wareing]

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.