---
title: "Constants"
manual: "TYPO3 Explained"
version: "13.4"
permalink: "https://docs.typo3.org/permalink/t3coreapi:globals-constants@13.4"
source: "ApiOverview/GlobalValues/Constants/Index.rst"
rendered: "2026-09-18T05:52:58+00:00"
---

# Constants {#constants}

Constants in TYPO3 define paths and database information. These values
are global and cannot be changed.
Constants are defined at various points during the [bootstrap sequence](https://docs.typo3.org/permalink/t3coreapi:bootstrapping@13.4).

To make the information below a bit more compact, namespaces were left out. Here
are the fully qualified class names referred to below:

Check `\TYPO3\CMS\Core\Core\SystemEnvironmentBuilder::defineBaseConstants()`
method for more constants.

****Table of contents****

-   [Security-related constant](https://docs.typo3.org/permalink/t3coreapi:security-related-constant@13.4)
-   [File types](https://docs.typo3.org/permalink/t3coreapi:file-types@13.4)
-   [HTTP status codes](https://docs.typo3.org/permalink/t3coreapi:http-status-codes@13.4)

## Security-related constant {#security-related-constant}

### FILE_DENY_PATTERN_DEFAULT {#file-deny-pattern-default}

Default value of [$GLOBALS\['TYPO3_CONF_VARS'\]\['BE'\]\['fileDenyPattern'\]](https://docs.typo3.org/permalink/t3coreapi:typo3confvars-be-filedenypattern@13.4).

-   **Defined in:**

    `\TYPO3\CMS\Core\Resource\Security\FileNameValidator::FILE_DENY_PATTERN_DEFAULT`

-   **Example:**

    `\\.(php[3-8]?|phpsh|phtml|pht|phar|shtml|cgi)(\\..*)?$|\\.pl$|^\\.htaccess$`

-   **Available in frontend:**

    Yes

### TYPO3 {#typo3}

TYPO3 still has some extension PHP script files executed in global context
without class or callable encapsulation, namely [`ext_localconf.php`](../../../ExtensionArchitecture/FileStructure/ExtLocalconf.md#file-extension-ext-localconf-php),
[`ext_tables.php`](../../../ExtensionArchitecture/FileStructure/ExtTables.md#file-extension-ext-tables-php) and files within `Configuration/TCA/Overrides/`.
When those files are located within the public document root of an instance and
called via HTTP directly, they may error out and render error messages. This can
be a security risk. To prevent this, those files **must** have a security gate
as first line:

```php
<?php

defined('TYPO3') or die();

// ... your code
```

It is defined to `true` in early TYPO3 bootstrap.

> [!NOTE]
> **See also**
>
> -   [ext_localconf.php](https://docs.typo3.org/permalink/t3coreapi:ext-localconf-php@13.4)
> -   [ext_tables.php](https://docs.typo3.org/permalink/t3coreapi:ext-tables-php@13.4)
> -   [Configuration/TCA/Overrides/](https://docs.typo3.org/permalink/t3coreapi:extension-configuration-tca-overrides@13.4)

## File types {#file-types}

<!-- TODO: no Markdown rendering for "versionchanged" -->

The PHP backed enum \TYPO3\CMS\Core\Resource\FileType has been
introduced as a drop-in replacement for the public FILETYPE_*
constants in \TYPO3\CMS\Core\Resource\AbstractFile. See
Migration.The constant file types have been marked as deprecated and will be
removed with TYPO3 v14.0. To be compatible with TYPO3 v12 and v13 use
the constants from \TYPO3\CMS\Core\Resource\AbstractFile.

Different types of file constants are defined in the enum
`\TYPO3\CMS\Core\Resource\FileType`. These cases are available for
different groups of files as documented in
[https://www.iana.org/assignments/media-types/media-types.xhtml](https://www.iana.org/assignments/media-types/media-types.xhtml)

These file types are assigned to all [FAL](https://docs.typo3.org/permalink/t3coreapi:fal@13.4) resources. They can, for
example, be used in [Fluid](https://docs.typo3.org/permalink/t3coreapi:fluid@13.4) to decide how to render different types
of files.

| Enum case | Value | Description |
| --- | --- | --- |
| `FileType::UNKNOWN` | 0 | Unknown |
| `FileType::TEXT` | 1 | Any kind of text |
| `FileType::IMAGE` | 2 | Any kind of image |
| `FileType::AUDIO` | 3 | Any kind of audio |
| `FileType::VIDEO` | 4 | Any kind of video |
| `FileType::APPLICATION` | 5 | Any kind of application |

### Migration {#migration}

Migrate all usages to use the new enum `\TYPO3\CMS\Core\Resource\FileType`
as follows:

-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_UNKNOWN` → `\TYPO3\CMS\Core\Resource\FileType::UNKNOWN->value`
-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_TEXT` → `\TYPO3\CMS\Core\Resource\FileType::TEXT->value`
-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_IMAGE` → `\TYPO3\CMS\Core\Resource\FileType::IMAGE->value`
-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_AUDIO` → `\TYPO3\CMS\Core\Resource\FileType::AUDIO->value`
-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_VIDEO` → `\TYPO3\CMS\Core\Resource\FileType::VIDEO->value`
-   `\TYPO3\CMS\Core\Resource\AbstractFile::FILETYPE_APPLICATION` → `\TYPO3\CMS\Core\Resource\FileType::APPLICATION->value`

## HTTP status codes {#http-status-codes}

The different status codes available are defined in
[EXT:core/Classes/Utility/HttpUtility.php (GitHub)](https://github.com/typo3/typo3/blob/13.4/typo3/sysext/core/Classes/Utility/HttpUtility.php).
These constants are defined as documented in
[https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml](https://www.iana.org/assignments/http-status-codes/http-status-codes.xhtml)