D7: hook_menu() variants

test.module.php

# test.module

<?php
/**
 * Implements hook_menu().
 *
 * @see https://api.drupal.org/api/drupal/modules%21system%21system.api.php/function/hook_menu/7.x
 */
function mymodule_menu() {
  # In main menu.
  $items['test-main-menu'] = array(
    'title' => t('Test main menu'),
    'menu_name' => 'main-menu',
    'weight' => 100,
    'type' => MENU_NORMAL_ITEM,
    'page callback' => 'drupal_goto',
    'page arguments' => array('search'),
    'access callback' => TRUE,
    'options' => array(
      'attributes' => array(
        'class' => 'custom-link' // Add custom class.
      )
    )
  );

  # Form callback.
  $items['test-form'] = array(
    'title' => t('Test form'),
    'description' => t(''),
    'page callback' => 'drupal_get_form',
    'page arguments' => array('form_example_form'),
    'access callback' => TRUE,
  );

  # Admin pages.
  # Callback return html.
  $items['admin/config/services/test'] = array(
    'title' => t('Test admin'),
    'description' => t('Test'),
    'page callback' => 'test_admin_page',
    'access arguments' => array('access administration pages'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'admin/test_admin_page.inc',
  );

  # Api pages.
  # Callback return array().
  $items['api/%'] = array(
    'page callback' => 'test_api',
    'access callback' => true,
    'page arguments' => array(1),
    'delivery callback' => 'drupal_json_output',
    'file' => 'api/test_api.inc',
  );

  return $items;
}