assetlocation.php

См. документацию.

<?php
namespace Bitrix\Main\Page;
 
class AssetLocation
{
    const BEFORE_CSS = 'BEFORE_CSS';
    const AFTER_CSS = 'AFTER_CSS';
    const AFTER_JS_KERNEL = 'AFTER_JS_KERNEL';
    const AFTER_JS = 'AFTER_JS';
    const BODY_END = 'BODY_END';
}
 
?>