Global space

Without any namespace definition, all class and function definitions are placed into the global space - as it was in PHP before namespaces were supported. Prefixing a name with :: will specify that the name is required from the global space even in the context of the namespace.

Example #1 Using global space specification

<?php
    namespace A::B::C;
 
 /* This function is A::B::C::fopen */
    function fopen() { 
         /* ... */
         $f = ::fopen(...); // call global fopen
         return $f;
    } 
?>