gistfile1.php

<?php
namespace Application\Form;

use Zend\Form\Form;

use Zend\Stdlib\Hydrator\ClassMethods as ClassMethodsHydrator;
use Zend\InputFilter\InputFilterProviderInterface;

class UserRegister extends Form implements InputFilterProviderInterface
{
    public function __construct($name = null, $options = array())
    {
        parent::__construct('user_register', $options);

        $this->setAttribute('method', 'post');
        $this->setHydrator(new ClassMethodsHydrator(false));
        
        // I create and add fieldset Application\Form\Fieldset\User
        $this->add(array(
            'type' => 'Application\Form\Fieldset\User',
            'options' => array(
                'use_as_base_fieldset' => true
            )
        ));

        $this->add(array(
            'name' => 'submit',
            'attributes' => array(
                'type' => 'submit',
                'value' => 'Register',
            )
        ));
    }

    public function getInputFilterSpecification()
    {
        return array(
            // here I want some filter and validator for my user.name
        );
    }
}