Main horizontal menu in Bitrix?

Question

1C-Bitrix

The header.php template file has the following code snippet in place of the main horizontal menu:

<?$APPLICATION->IncludeComponent(
  "bitrix:menu",
  "horizontal_multilevel",
  Array(
    "ROOT_MENU_TYPE" => "top", 
    "MAX_LEVEL" => "3", 
    "CHILD_MENU_TYPE" => "left", 
    "USE_EXT" => "Y", 
    "MENU_CACHE_TYPE" => "A",
    "MENU_CACHE_TIME" => "3600",
    "MENU_CACHE_USE_GROUPS" => "Y",
    "MENU_CACHE_GET_VARS" => Array()
  )
);?>

Almost everything is clear here, but where is the menu code itself? Project search yields:
Side menu is stored in:
bitrix\wizards\bitrix\demo\public_files\en\personal
Top menu is stored in:
bitrix\modules\main\install\components\bitrix\menu\templates\catalog_vertical
What is the storage principle and why
don't they store these files in bitrix\templates\template_name\?

Answer 1

Most likely it is in bitrix\templates\.default\components\bitrix\menu\templates\catalog_vertical\template.php
And the menu items are in the root of the site /.top.menu.php