Example of using subforms

I notice on the documentation for CForm that "Sub-forms are mainly used to handle multiple models. For example, in a user registration form, we can have the root form to collect input for the user table while a sub-form to collect input for the profile table."

How are subforms contructed in Yii? Any examples out there?

Thanks,

Jon

This example is close:

http://www.yiiframework.com/doc/cookbook/29/