Описание тега psr-0
PSR-0 describes requirements that must be adhered to for autoloader interoperability in PHP.
PSR
Proposing a Standards Recommendation.
PSR-0Aims to provide a standard file, class and namespace convention to allow plug-and-play code.
PSR-1Aims to ensure a high level of technical interoperability between shared php code.
PSR-2Provides a Coding Style Guide for projects looking to standardise their code.