[ic] How to stop zero cost shipping

[Stewart Barnett]

One more for the group while I am on a roll.

There are occasionally orders that come through with a shipping cost of $0.00. 
I can reproduce the problem consistently by selecting a valid shipping method with an 
invalid zipcode. I get an error on the screen that clearly states : 
"Zero cost returned for mode Foo, geo code XXX"

Now lets just say hypothetically that a customer doesn't pay attention to the bright red 
warning on the page and hits the place order button. ( I know this never happens but 
humor me for the sake of this discussion) The order will still go through. 

 I can not figure out what to put in the checkout_profile that will stop the order if 
shipping is a zero cost. There is not much documentation on just what operations are 
available within a profile, but I know a simple blah=required won't do the job. There is 
an option in the shipping method editor that says "Allow to be zero cost", but it doesn't 
change a thing in the shipping.asc file.

I can't be the only one who suffers this loophole. Any tidbits of wisdom?

Stew