A class that implements an interface cannot override a constant defined in the interface. But any child class that extends from the implementing class... can?

interface_mania.php

<?php

/**
 * A class that implements an interface cannot 
 * override a constant defined in the interface. 
 * But any child class that extends from the 
 * implementing class... can? 
 * 
 * o_O
 */

interface FooInterface
{
    /**
     * Define a constant
     */
    const FOO = 'foo';
}

class Bar implements FooInterface
{
    /**
     * As noted in the PHP docs:
     *
     * An implementing class can 
     * not override an interface 
     * defined constant...
     */
    const FOO = 'bar'; // FATAL ERROR! 
}

class Baz extends Bar
{
    /**
     * However, a child of an 
     * implementing class can 
     * override an interface 
     * defined constant :)
     */
    const FOO = 'baz'; // WORKS!
}