/**
  * Add an array of additional allowed extensions
  * @static
  * @param $array
  */
 static function add_allowed_extensions($array = null)
 {
     if (empty($array)) {
         return;
     }
     if (is_array($array)) {
         self::$allowed_extensions = $array;
     } else {
         self::$allowed_extensions = array($array);
     }
 }
<?php

$config = Config::inst();
$config->update('DMSDocument_versions', 'enable_versions', true);
DMSSiteTreeExtension::show_documents_tab();
//show the Documents tab on all pages
DMSSiteTreeExtension::no_documents_tab();
//and don't exclude it from any pages
DMSDocumentAddController::add_allowed_extensions();
//add an array of additional allowed extensions
define('DMS_DIR', 'dms');
if (!file_exists(BASE_PATH . DIRECTORY_SEPARATOR . DMS_DIR)) {
    user_error("DMS directory named incorrectly. Please install the DMS module into a folder named: " . DMS_DIR);
}
CMSMenu::remove_menu_item('DMSDocumentAddController');
ShortcodeParser::get('default')->register('dms_document_link', array('DMSShortcodeHandler', 'handle'));
if ($config->get('DMSDocument_versions', 'enable_versions')) {
    //using the same db relations for the versioned documents, as for the actual documents
    $config->update('DMSDocument_versions', 'db', $config->get('DMSDocument', 'db'));
}