Sorry, I submitted this to the 'add notes' for the online manual thinking that was where I might get information.

What I did is  cut-&-pasted the code from documentation for the function array_multisort() into a brand new PHP script and added some print_r() calls. The function array_multisort() doesn't work as adverstised. :] It generates an error: Warning: Argument 3 to array_multisort() is expected to be an array in array_multisort.php on line 9 

Here is the PHP file array_multisort.php: 
<pre> 
<?php 

$ar = array (array ("10", 100, 100, "a"), array (1, 3, "2", 1)); 

print_r($ar); 

array_multisort ($ar[0], SORT_ASC, SORT_STRING, 
$ar[1], SORT_NUMERIC, SORT_DESC); 

print_r($ar); 

?> 
</pre> 

Can anyone assist?