* Use namespaces for all classes;

* Abstract classes are often prefixed with ``Abstract``;

* Prefix abstract classes ``Abstract``. Please note some early Symfony2 classes

do not follow this convention and have not been renamed for backward compatibility

reasons. However all new abstract classes must follow this naming convention;

* Suffix interfaces with ``Interface``;

* Suffix traits with ``Trait``;

* Suffix exceptions with ``Exception``;

* Use alphanumeric characters and underscores for file names;

* Don't forget to look at the more verbose:doc:`conventions` document for