As markus_petrux wrote:

It seems that the new addition to CCK, the new hook_widget_settings_alter() opened Pandora's box.

There are quite a few modules that attach their own logic to CCK fields. Up until now those modules had to have their own DB or set their own variables.

In CCK 2.5, hook_widget_settings_alter() got in, which allows your module to hook into the field settings, and rely on CCK to save and load those settings when needed.

But that’s not all - as the settings are becoming part of the CCK field defention it means that when you’ll export the CCK to code - your module settings will be there. Your module now actually has import/ export functionality without you even having to bother about.

All you need is to pack your CCK code export in Features. Here’s an example that will add some data to number fields:

<?php
/**
 * Implementation of hook_widget_settings_alter().
 */
function foo_widget_settings_alter(&$settings, $op, $widget) {
  $widget_types = array('number');
  if ((!empty($widget['type']) && in_array($widget['type'], $widget_types)) || (!empty($widget['widget_type']) && in_array($widget['widget_type'], $widget_types))) {
    switch ($op) {
      case 'form':
        $settings['foo'] = array(
          '#type' => 'checkbox',
          '#title' => t('Some settings'),
          '#options' => array(0 => t('Disabled'), 1 => t('Enabled')),
          '#default_value' => !empty($widget['foo']),
        );

        break;
      case 'save':
        $settings[] = 'foo';
        break;
    }
  }
}

/**
 * Check if 'foo' is enabled on a field.
 */
function foo_is_field_foo($field_name) {
  $field = content_fields($field_name);
  return !empty($field['widget']['foo']);
}
?>