(PHP 5 >= 5.3.0, PHP 7, PHP 8)
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:
Example #1 Declaring a single namespace with hierarchy
<?php
namespace MyProject\Sub\Level;
const CONNECT_OK = 1;
class Connection { /* ... */ }
function connect() { /* ... */ }
?>MyProject\Sub\Level\CONNECT_OK,
class MyProject\Sub\Level\Connection and function
MyProject\Sub\Level\connect.