A problem with nested forms arises when the outer form is submitted and what should happen with the fields of the inner forms.
Consider the following form setup in a page: outer inner1 inner2 inner3 inner4 If you submit the outer form, what should you process now? All inner forms? In what order? What happens if validation of one of the inner forms fails? My proposal is to treat the outer form the same as submitting one of the inner forms: don't process the input of the form that was not explicitly submitted. The reason is that it breaks the encapsulation of the inner forms and therefore can introduce subtle bugs or unwanted behavior. If a user of the nested form does want to process the inner forms, it is a matter of implementing a form visitor that visits all or a particular inner form and invokes the processing. In this case, the user is himself responsible for breaking the encapsulation, not us. The vote: don't process inner form fields when the outer form is submitted [ ] Yes, don't process those pesky little fields [ ] No, process them as if they were part of the outer form Martijn
