PHP references question

[AndrewD]

I suspect I'm missing something very obvious here. Can someone explain the behaviour of this code:

<?php

$test = "12345";
$anothertest = "";
$yetanothertest = "";

function getref() {
	global $test;
	global $anothertest;
	global $yetanothertest;

	$anothertest =& $test;
	$GLOBALS['yetanothertest'] =& $test;

	echo "<br /><br />Inside<br />";
	echo "test:".$test."<br />";
	echo "anothertest:".$anothertest."<br />";
	echo "yetanothertest:".$yetanothertest."<br />";
}

getref();

echo "<br /><br />Outside<br />";
echo "test:".$test."<br />";
echo "anothertest:".$anothertest."<br />";
echo "yetanothertest:".$yetanothertest."<br />";

echo "<br /><br />";

?>

which prints out

Inside
test:12345
anothertest:12345
yetanothertest:

Outside
test:12345
anothertest:
yetanothertest:12345

In other words, within the function, the reference assignment seems to have updated $anothertest but not $yetanothertest, yet having left the function, it's the other way round.

With direct assignments ($A = $B) instead of references ($A =& $B), both of the global variables are updated and correctly displayed inside and outside the function.