$default  = sort([$a, $b, $c]);
$reverse  = sort([$a, $b, $c],  "r");
$numup    = sort([$a, $b, $c],  "n");
$numdown  = sort([$a, $b, $c],  "nr");
$lexup    = sort([$a, $b, $c],  "f");
$lexdown  = sort([$a, $b, $c],  "fr");
$foldup   = sort([$a, $b, $c],  "c");
$folddown = sort([$a, $b, $c],  "cr");
