Need help building CCK fieldset/widgets D5

What is the bare minimum hooks / cases to setup a custom cck field and widget? What I'm trying to do here is just a simple select list with 2 options. No validations required.

The database is created, the form field shows, however, the values doesn't get saved to db when i submit.
Any help?

function zroy_reference_widget_info() {
  $option_types = array('zroy_reference');
  return array(
    'zroy_options_select' => array(
      'label' => t('Select list'),
      'field types' => $option_types,
    ),
  );
}

function zroy_reference_widget($op, &$node, $field, &$node_field) {
  switch ($op) {
    case 'form':
      $form = array();
      $form[$field['field_name']] = array('#tree' => TRUE);
      
      $form[$field['field_name']]['keys'] = array('#type' => 'select',
                                           '#title' => t($field['widget']['label']),
                                           '#multiple' => TRUE,
                                           '#options' => array('1' => 'a', '2' => 'b'),
                                           );
      return $form;
      break;
  }
}
function zroy_reference_widget_settings($op, $widget) {
  switch($op) {
    case 'form':
      $form = array();
      return $form;
  }
}

function zroy_reference_field_info() {
  return array(
    'zroy_reference' => array('label' => 'zroy_reference'));
}

function zroy_reference_field_settings($op, $field) {
  switch($op) {
    case 'database columns':
        $columns = array(
          'value' => array('type' => 'varchar', 'not null' => TRUE, 'default' => "''", 'sortable' => TRUE),
        );
        if ($field['max_length'] == 0 || $field['max_length'] > 255) {
          $columns['value']['type'] = 'longtext';
        }
        else {
          $columns['value']['length'] = $field['max_length'];
        }
        return $columns;
  }
}

function zroy_reference_field($op, &$node, $field, &$items, $teaser, $page) {

}