• Syntax: void fields_for ( $object_name, &$object)
• Description: Creates a scope around a specific model object like form_for, but doesn't create the form tags themselves. It is suitable for specifying additional model objects in the same form.
• Example:

<?php $person_form = $this->form_for('person', $Person, array('url' => array('action'=>'update'))); ?>
First name: <?= $person_form->text_field('first_name'); ?>
Last name : <?= person_form->text_field('last_name'); ?>
<?php $permission_fields = $form_helper->fields_for('permission', $Person->permission); ?> 
Admin? : <?= $permission_fields->check_box('admin'); ?> 
<?= $person_form->end_form_tag(); ?>

Note: This also works for the methods in FormOptionHelper and DateHelper that are designed to work with an object as base. Like collection_select and datetime_select. This note needs more of an explanation and also references.