The goal for this guide is to increase consistency in style across disparate PHP projects written by multiple authors. It is intended to serve as a reference for reasonable expectations so as to reduce cognitive friction when scanning code from different projects.
This style guide is not a moral or ethical statement. It is an attempt to agree upon a common set of rules, requirements, recommendations, idioms, and approaches for code formatting. Any such guide is by nature arbitrary. The benefit is in the adherence to the rules, not in the rules themselves.
There are times when a particular rule or recommendation will not make sense in a particular limited context. Breaking the rule or recommendation in that particular limited context does not mean the remainder of the codebase under consideration is not PSR-1 compliant; instead, it is to be recognized as a regrettable but necessary departure from the guide for that one circumstance.
This guide is derived from commonalities between Horde, PEAR, Solar, Symfony, Zend, and other projects.