I am not sure what the correct name is for this feature, but it does make function calling more convenient. Take this for an example:

<?php

function hold_the_line($soldier='Major Rawne',
$regiment_leader='Colonel-Commissar Gaunt',
$planet='Tanith') {
	print "Soldier: ".$soldier;
	print "Regiment Leader: ".$regiment_leader;
	print " from ".$planet;
}

hold_the_line($planet='Vervunhive');

?>

This is what I am talking about. PHP will completely ignore, deliberately or other, the $planet, thus outputting,

Soldier: Vervunhive, Regiment Leader: Colonel-Commissar Gaunt from Tanith

This makes default arguments all the more difficult. If you do this in Python,

def hold_the_line(soldier='Major Rawne',
regiment_leader='Colonel-Commissar Gaunt',
planet='Tanith'):
	print "Soldier: " + soldier
	print "Regiment Leader: " + regiment_leader
	print " from " + planet

hold_the_line(planet='Vervunhive')

you would get this,

Soldier: Major Rawne
Regiment Leader: Colonel-Commissar Gaunt
 from Vervunhive

Cool, eh? PHP needs this. Not sure if it’ll appear in PHP6.