Actually, I didn't know. Look at this examples
* https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide-meta.md 
* https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md 
* https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-4-autoloader-examples.md