$cache_msg not defined in glossary.admin.inc

http://localhost/d6/admin/settings/glossary

notice: Undefined variable: cache_msg in /Users/robert/Sites/d6/sites/all/modules/glossary/glossary.admin.inc on line 28.
notice: Undefined variable: cache_msg in /Users/robert/Sites/d6/sites/all/modules/glossary/glossary.admin.inc on line 64.

I don't understand where $cache_msg is supposed to come from?

function glossary_general_settings_form() {
  $form = array();

  $form['general'] = array(
    '#type' => 'fieldset',
    '#title' => t('General settings'),
    '#collapsible' => true,
    '#collapsed' => false,
    '#description' => $cache_msg,
    );

  $form['general']['glossary_disable_indicator'] = array(
    '#type' => 'checkbox',
    '#title' => t('Allow the user to disable glossary links.'),
    '#default_value' => variable_get('glossary_disable_indicator', false),
    '#description' => t('Determines whether or not the individual user may disable the Glossary indicators.'),
    );

  $form['general']['glossary_hide_menus'] = array(
    '#type' => 'checkbox',
    '#title' => t('Hide unused input format tabs.'),
    '#default_value' => variable_get('glossary_hide_menus', false),
    '#description' => t('Determines whether or not to hide settings tabs for input formats that are not glossary-enabled. Changing this setting may require you to clear the cache_menu table.'),
    );

  $click_options = array(
    t('Show only the single term.'),
    t('Advance the whole glossary to the term.'),
    );
  $form['general']['glossary_click_option'] = array(
    '#type' => 'radios',
    '#title' => t('Clicking on a term link will'),
    '#options' => $click_options,
    '#default_value' => variable_get('glossary_click_option', 0),
    '#description' => t('Changing this setting may require you to clear the cache_filter.'),
    '#prefix' => '<div class="glossary_radios">',
    '#suffix' => '</div>',
    );

  $form['glossary_page'] = array(
    '#type' => 'fieldset',
    '#title' => t('Glossary Page'),
    '#collapsible' => true,
    '#collapsed' => false,
    '#description' => $cache_msg,
    );