PSR-2: https://github.com/php-fig/fig-standards/blob/master/accepted/PSR-2-coding-style-guide.md
(Excerpt)
This guide extends and expands on PSR-1, the basic coding standard.
The intent of this guide is to reduce cognitive friction when scanning code from different authors. It does so by enumerating a shared set of rules and expectations about how to format PHP code.
