Arracy Checbox Form Validation help

Hi there

I am trying to validate a new field that i have entered in a wordpress form – ZM Ajax Login and Register

I have copied the other fields but now cionsued on how to validate the check box. To register the person must have it ticked.

This is what the field looks like:

$this->prefix . '_terms_condition' => array(
                                                                'title' =>__( 'Terms & Conditions', ZM_ALR_TEXT_DOMAIN ),
                                                                'type' => 'checkbox',
                                                                'href' => '<a href="http://www.google.com"></a>',
                                                                'required' => true,
                                                                'label' => 'Please tick the box to download terms & Conditions',
                                                                'extra' => 'autocorrect="none" autocapitalize="none"',
                                                                ),

And here is what the other validation fields look like.

'valid_username' => array(
                'description' => null,
                'cssClass' => 'noon',
                'code' => 'success'
                ),
            'username_exists' => array(
                'description' => __('Invalid username', ZM_ALR_TEXT_DOMAIN ),
                'cssClass' => 'error-container',
                'code' => 'show_notice'
                ),
            'invalid_username' => array(
                'description' => __( 'Invalid username', ZM_ALR_TEXT_DOMAIN ),
                'cssClass' => 'error-container',
                'code' => 'show_notice'
                ),
            'username_does_not_exists' => array(
                'description' => __( 'Invalid username', ZM_ALR_TEXT_DOMAIN ),
                'cssClass' => 'error-container',
                'code' => 'show_notice'
                ),

Please any help wpuld be appreciated