Description:
------------
The page describing how to pass variables by reference 
(http://my.php.net/manual/en/language.references.whatdo.php)
 doesn't mention another technique of passing by reference which is to put the 
ampersand on the variable when the function is being called, rather than in the 
function definition.

As a result, I'm not sure what the intended behaviour is eg:

Could it cause a problem?
Perhaps it's some side-effect of being able to declare arrays by reference that 
wasn't intended?
Perhaps it is a handy tool? 

The documentation should mention it and clarify.

Test script:
---------------
<?php
$a = 0;
testRef($a);
echo "no ref :    $a \n";
$a = 0;
testRef(&$a);
echo "input ref : $a \n";
$a = 0;
testRef($a);
echo "function definition ref :  $a \n";
$a = 0;
testRef(&$a);
echo "function definition and input ref :  $a \n";
function testRef($a) {
    $a +=1;
}
function testRef2(&$a) {
    $a +=1;
}
?>

Expected result:
----------------
I don't know, that's the problem with the documentation. Maybe 'input ref' should 
actually be 0?

Actual result:
--------------
no ref : 0 
input ref : 1 
function definition ref : 0 
function definition and input ref : 1