drupal/core/modules/menu/menu.install

<?php

/**
 * @file
 * Install, update and uninstall functions for the menu module.
 */

/**
 * Implements hook_schema().
 */
function menu_schema() {
  $schema['menu_custom'] = array(
    'description' => 'Holds definitions for top-level custom menus (for example, Main menu).',
    'fields' => array(
      'menu_name' => array(
        'type' => 'varchar',
        'length' => 32,
        'not null' => TRUE,
        'default' => '',
        'description' => 'Primary Key: Unique key for menu. This is used as a block delta so length is 32.',
      ),
      'title' => array(
        'type' => 'varchar',
        'length' => 255,
        'not null' => TRUE,
        'default' => '',
        'description' => 'Menu title; displayed at top of block.',
        'translatable' => TRUE,
      ),
      'description' => array(
        'type' => 'text',
        'not null' => FALSE,
        'description' => 'Menu description.',
        'translatable' => TRUE,
      ),
    ),
    'primary key' => array('menu_name'),
  );

  return $schema;
}

/**
 * Implements hook_install().
 */
function menu_install() {
  $system_menus = menu_list_system_menus();
  $t = get_t();
  $descriptions = array(
    'navigation' => $t('The <em>Navigation</em> menu contains links intended for site visitors. Links are added to the <em>Navigation</em> menu automatically by some modules.'),
    'user-menu' => $t("The <em>User</em> menu contains links related to the user's account, as well as the 'Log out' link."),
    'management' => $t('The <em>Management</em> menu contains links for administrative tasks.'),
    'main-menu' => $t('The <em>Main</em> menu is used on many sites to show the major sections of the site, often in a top navigation bar.'),
  );
  foreach ($system_menus as $menu_name => $title) {
    $menu = array(
      'menu_name' => $menu_name,
      'title' => $t($title),
      'description' => $descriptions[$menu_name],
    );
    menu_save($menu);
  }
}

/**
 * Implements hook_uninstall().
 */
function menu_uninstall() {
  menu_router_rebuild();
}

/**
 * Moves menu settings from variables to config.
 *
 * @ingroup config_upgrade
 */
function menu_update_8000() {
  update_variables_to_config('menu.settings', array(
    'menu_main_links_source' => 'main_links',
    'menu_secondary_links_source' => 'secondary_links',
  ));
}