Nested switch in PHP 5.6 syntax

I had a bit of trouble with nested selects in PHP 5.6 (not sure of the differences for other versions).  I went down the wrong path of thinking my problem was with global vs. local variable scope, but that wasn't the case. The PHP documentation doesn't go enough detail for nested switches as far as having multiple default outcomes, but this works.  Example:

$color = "red";
$size = "large";

switch ($color) { 
   case "blue": $sku = "5327"; break; 
   case "white": $sku = "5328"; break; 
   case "red":   
      switch ($size) {   
         case "small": $sku = "5329-1"; break;   
         case "medium": $sku = "5329-2"; break;    
         case "large": $sku = "5329-3"; break;    
         default:    
            $sku = "5329";    
            break;  
      };                 
      break; 
   default:  
      $sku = "0";  
      break;
}