TYPO3 files and user files

All files in the TYPO3 web site directory hierarchy are divided into TYPO3 files and user files.

TYPO3 files are files that come with the TYPO3 source package released by the TYPO3 association. This includes files inside the typo3/ directory and the file named index.php in the root of the TYPO3 installation.

All other files are user files. This for example includes extensions, files in the fileadmin/ directory or files generated by TYPO3 (like configuration files, thumbnails or temporary CSS files). User files are not allowed in the folder typo3/.

These CGLs are valid for all TYPO3 files and for those user files, which are to be generated or processed by the TYPO3 Core like for example LocalConfiguration.php or AdditionalConfiguration.php.