Thanks Dieter, exactly what I was searching for!

Damir Bartakovic writes:

...

I am using ZnolkSQLWizard and it creates output like <INPUT TYPE="TEXT" NAME="table.name"> ...

Now I am trying to force the user not to leave the field blank. Usually it works with <dtml-unless "somevariable"> ... once again! ....</dtml-unless>

but with <dtml-unless "table.name"> ... I get the error: Error Type: NameError Error Value: table (The Traceback is at the end)

Like it seems it don't like the '.'? It likes '.' but interprets it differently:

Inside "...", you are in the realm of Python expressions. In Python, the "." is not part of a name (as in DTML) but it is an operator: the left operand is an object, the right one a name and the result is the object's attribute of the given name.

You can use, e.g. "_['table.name']" to access the object with name "table.name" from Python.

The official Zope book and

URL:http://www.dieter.handshake.de/pyprojects/zope/book/chap3.html

will tell you more about these issues.