[Twisted-web] How to pass invisible values with annotate.TypedInterface

[Michael Wilson]

My forms are modeled after the examples in examples/customform.py, and
I try and use this standard form definition in multiple places.

In some cases, I would like to pass an invisible value with the form.
I know of two ways to do this:

1. By adding arguments to the form URL (
action="./freeform_post!!doSomething?myarg1=...")
2. By adding invisible fields to the form. 

What's the best way to do this? 

P.S. I've looked at the examples and the code, can't find the answer. 

Thanks!