[support] general form errors

[Don Pickerel]

I have a form of (n) checkboxes that are generated at creation time. I'd 
like to set an error if none of the checkboxes are checked, but not any 
one of the checkboxes in particular.

There doesn't seem to be a good way to set an error except for setting 
an error on every checkbox.

Does anyone have a better way to tell the user not to send a blank form?

Drupal 6.

Thanks.
-Don-