(PHP 5 >= 5.3.0)
Much like directories and files, PHP namespaces also contain the ability to specify a hierarchy of namespace names. Thus, a namespace name can be defined with sub-levels:
Exemplo #1 Declaring a single namespace with hierarchy
<?php
namespace MyProject\Sub\Level;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
?>